Your favorite video game glitches?

You know! Those game glitches which are so weird or so damn helpful they become your absolute favorite glitches of all time?
 
My favorite HAS to be Fallout 3 and the flying DEATHCLAW!!! 
 

mountainlion-man from RDR
 
i mean, when i first saw that, i had been up for 30 something hours (i get really bad insomnia), i thought i was seeing things, i freaked out man. i freaked out.

RDR - Riding a horse, without the actual horse

Mountain lion with a human model from Red Dead Redemption is preeeeeeetty good.

Missingno. Bar none.

Screen warping from the original Link's Awakening on GameBoy.

my favorite was tony hawk underground 2. the glitches in those games were awesome. in the training level (first level) there was a way to get underground to walk. you could see people while in the puddle. there was also another one to sit in the taxi. pretty crazy ones.

@HistoryInRust said:

Missingno. Bar none.

Also the one that gives you achievements in AC after falling forever through the floor.

The swingset glitch from GTA IV. That's a great one.

Playing Battlefield 1942 on my old Kyro II card was all sorts of messed up. In fact, games rarely worked fine with that piece of junk (due to no hardware T&L support).

Also the W-Item gltich in FFVII.

Shut up! I could have taken ruby without it XD maybe.

Super bouncing in Halo 2. Gosh, that game was so much better with all the glitches.

I had a funny glitch of my own:

From something that happened to me personally: Hidden & Dangerous on the PC. I was playing it with a friend and in the very first mission we had one guy in the squad lie down in front of a rock. He proceeeded to fall through the level and to his doom into a black hole underneath the level. This was like 5 minutes into the very beginning of the game.

Oh, and the nazi soldiers on the bridge we had to cross could headshot the entire squad with their MP5 machine guns. From approximately 2-3 kilometers away. This happened again and again.

Fun game.

My all-time favorite, however, is Jerry the retarded horse, from Two Worlds.

(Wait until at least 1:30)

Nothing really comes to mind. Glitches tend to ruin/hurt the game. Never had a fun one. At least not one that I knew was a glitch.

The rare candy glitch in the original Pokemon games wasn't bad.

The somewhat infamous Ermac glitch in the original Mortal Kombat where Scorpion would be red instead of yellow.. Gave birth to a pretty cool character, in my opinion. May not be my absolute favorite, but it's what came to mind first.