Nothing epic but i often blind or stun myself with my own grenades.

I jumped out of the barbershop window in Favela, trying to flank a guy in mid air, his teammate shot me in mid air and i broke my legs on the ground, killing me, and giving my enemy an assisted suicide.

I had ran into a room, threw a stun grenade, of course stunned myself, and I figured I was going to die, so mine as well try to blindfire and take the enemy down.  I ended up getting killed and watching my Killcam; the guy wasn't even stunned by the grenade, he just went prone in the corner and watched me stab the air three times and empty an entire clip while spinning in circles before walking up and stabbing me in the back.

Well, this happened twice but I threw a care package in a corner and killed a spawning teammate when the box fell.

I died from getting hit in the head with a smoke grenade.

when i first started i ran into a room behind a guy he cleaned out the room.... than knifed me... i thought he was my teammate

One hilarious moment stands out in my mind. 
 
My friends and I were playing search and destroy.  I was the only one still alive on my team sneaking around trying to kill the remaining members of the other team.  Long story short, I threw a flash bang up a set of stairs, it bounced back and somehow blew up an explosive barrel right next to me.  

I was playing with Pessh/Skye (so I have proof) and was about to stab a guy defusing a bomb in Search and Destroy when I somehow missed and we lost.

I often throw a flash if i think someone is coming near me which bounces off a wall so i flash myself and then i panic so i throw a frag which will...well i die at the end.

Let's see, I called in a supply drop, and saw a riot shielder running up to try and steal it. I throw a semtex, at the exact moment the crate falls. Semtex sticks to crate, kills me, and he gets the crate. It was an AC130.

Killed a teammate with a care package on accident, got knifed from behind, and the enemy stole my care package that I just killed my teammate with.

thinking I have any skill in this game

CTF
Score is tied 2-2 in overtime,
I'm running the flag back to my base,
And the battery in my controller dies 3 steps from the win. 
Half the enemy team is on me, I die they return theirs steal ours and run it back for the win.

You know how you sometime get into those awkward situations when you are walking down the street and another person is coming towards you and you both try to step aside, but both go in the same direction so it takes you several tries to get around? I had something like this happen except in reverse when both me and my brother stumbled into each other and started trying to knife one an other, we both sidestepped and dodged each other knife attempts over and over and could not connect for at least 3-4 tries from each of us, spinning and strafing like 2 retards until one of us finally connected (don't even remember who) laughed till I had to go take a leak.

On Terminal, I was care package knifing (I was bored). I was in the airplane and lunged and missed a kid 4 times in a row. I eventually got him, but it was still awful :(

Threw a knife at an enemy that was directly in front of me, missed. He grabbed the knife, turned around, and killed me with it before I could shoot him proper.

" Threw a knife at an enemy that was directly in front of me, missed. He grabbed the knife, turned around, and killed me with it before I could shoot him proper. "

Nothing hugely epic, but I have my matches where I'll basically outline the enemy with bullets and miss the easiest kills imaginable. I also have a tendency to flash my own teammates or frag them while playing hardcore.

in Derail
with a 23 killstreak with the nuke equipped
I plant a claymore at the corner of the entrance of the big building and hide behind barrels,
I come out due to alot of my team being around, as I walk to the entrance, a crouched guy turns the corner which I knife accordingly as he walked to the entrance which in turn, triggered my claymore... which then exploded in my face ending my 24 killstreak, one kill away from the nuke lol

It was down to 1v1 on SnD, and I was standing over a guy as he was planting a bomb. I wanted to fuck with him so I just stood over him with a shotty trained at his head thinking I'd shoot him once he turned around. He planted it, I killed him, he had martyrdom. I died. Yeah.

 ground war   domination, Taking B on Derail. 4 of us were. We weren't coordinated. A guy with akimbo rangers comes down and kills us all ,one shell each. Lame.......... he must of had steady aim.

I played online.

" I played online. "

CTF, was in overtime and I did not know all you had to do was touch the enemy flag. So like the camping faggot I am i sat quietly near our flag and waited for a dude to run up on it, thinking heheheh ill get the extra 50 points and wait for this guy to pick it up and then kill him. Then he touched it, we lost, and god damn i felt like an idiot

Not my fault, but here is the biggest epic fail I have had on the game:  
 
Playing on terminal, domination, minding my own business when some dude kills me. 
I spawn, immediately knifed the moment I spawn, respawn by A. 
The second I spawn a noob tube directly hits me, I respawn outside near the airplane. 
Before I even have a chance to move anywhere a care package lands on my face and I die. 
 
Yeah I was laughing yet also fairly pissed (insta dying 3 times in a row is annoying).

i was fighting a guy with a shield ran out of ammo and we were like stearing at each other,  throw a semtex on his shield  try to run away but he runs after me and we both explode

I was playing Free-For-All on Karachi. I saw an enemy that went into a building. I ran into the building, and tossed a stun grenade. The grenade then proceeded to land in front of my feet instead of behind a wall, blinding and disorienting me. I was then forced to watch an extremely slow death as the guy came around the corner and knifed me in the face. Fail.

" Well, this happened twice but I threw a care package in a corner and killed a spawning teammate when the box fell. "

Flashbanging myself twice in a row.

" @CitizenKane:  This but it was my own grenade :(  Crushed by my own care packages, falling off highrise, flashing or stunning self in front of half the enemy team etc etc "

I was playing wasteland on ground war with my trusty barret 50cal. Somehow I get behind three enemies in a trench. They are completely oblivious to my presence. As I aim down the sights I notice they are all lining up perfectly. In my head im thinking 'triple collateral'. I have never hit a triple in all my time with CoD4, WaW or MW2. My moment had finally come. There was no way I could miss. So without further ado, I take the shot. 

 For a moment I couldn’t understand what had happened. I here my rifles bang, but I hear no hitmarkers and I have gained no points. Yet a gargantuan cloud of smoke emanates from the trench were those three men were just moments before.
 
  My teammates predator missile has blown them all to smithereens.
To make things worse, he is triumphantly boasting about his triple kill over his headset.

" I played online. "

dying

Dropping care packages on top of building. Where none of my teammates could access it.

"  

"

I was 1 kill away from getting an EMP when the sky was filled with an enemy AC130, Harrier and Pavelow.... saw a guy hiding in the window overlooking the storage in Skidrow so i thought I'd throw a Semtex in there..... and as has happened countless times before i had Tactical Insertion on and didn't realize it.  His killcam was of me running, walking slowly and dropping a TI, then killing me..... twice.

I was on a 23 kill streak on Safehouse, with a nuke equipped. I was outside, and looked at my radar and a predator missile dropped on my ass. Ouch...

Once agro'd a random mob in Black Wing Lair while in a 40 player raid in WoW.  I didn't notice because he didn't follow me initially, it wasn't until a minute or so later when I had rejoined my group that I realized he had pathed a different way to get to me, bringing with him a few hundred of his friends.    Safe to say I wasn't very popular for a good week or so after my fully epic'd hardcore raid guild was wiped in seconds by 'the new guy' lol.

I called in a care package and as usual, few of my nearby teammates came running in hopes of ninja'ing the package in case I get sniped or something. Well the package lands on this little bump in the terrain, giving it some real horizontal velocity, killing all three of us and then some player ends up stealing in.

Lining up a perfect headshot on an enemy sniper in that big outdoor map with the underground tunnels and trenches. I stealthed half way across the map and was in the grass behind a vehicle, but I managed to spot him (he was murdering my team).
 
Pulled the trigger, felt the Intervention's kick, re-centered and saw a cloud of smoke from a Grenade. On top of not getting the kill, I immediately get razed by automatic fire.
 
Or emptying a half a mag into a guy only to get an assist from a friendly blind firing a hundred feet away. At a different enemy.
 
The one thing I hate though is when you know an enemy's coming so you crouch and wait, only for two teammates to run at you right when "Enemy Predator Missile Inbound!" is heard. Oh yeah, on Quarry, the red warehouse area...the building closest to the level boundary...I was right outside the door when I hear the warning and see the red circle appear. I turn around and sprint right into the doorway. I would have lived if I had made it inside the building.
 
Instead, a teammate goes sprinting out of the door the same time I try to go in, even though the game yelled at us telling a missile was inbound. Another teammate was close by, and *bam*. Triple kill. I watched the killcam going "Damn you, Damn you, Damn you."
 
Then again, there's also the times where it seems you're invincible or amazing, so it evens out. I don't think I'll ever forget my first Care Package/Predator Missile/Airstrike combo. Sometimes you just go on crazy kill sprees out of no-where.
 
@Lazyaza: I remember when Gnomer was glitched (not sure if it still is, haven't played in forever) and if you were too low of a level, you would aggro the fucking boss from the beginning of the damn instance, bringing almost the entire place with him. Like, you would get down the hallway and just see a freaking sea of enemies hauling ass ready to rape you.

Tried to nade a camper in Hardcore Team Deathmatch in Terminal. He was above where I was so I was trying to semtex the roof just above him. Instead I missed, semtex hit the wall next to me, I was stuck on some baggage and couldn't flee. Death.
 
My mate had died prior to that and was watching my progress.
 
Suffice to say he laughed. A lot