This post is bought to you by my last "New Game" generation.
 
I "rolled" a new map and naturally spawned on sand as you always seem to do.  Only before i could even walk 1 step the spot i was standing on and a hole at least 8 blocks in every direction collapsed.  I fell to a depth that left me with 2 hearts only to turn around and find a Skellie spawner right behind me.   Thankfully the respawn moved me to a new spawn point beside the gaping hole in the earth.
 
Whats the most amusing ill fated end you ever met with?

I had recently made a diamond pickaxe, sword and full steel armor when I went exploring a cave and was punched down into a pool of Lava by a zombie.  
 
Good times. 

the holocaust

" the holocaust "

"Lets see what all the buzz of single player is about..." 
SSSSSssss 
*explode* 
"I'm alive!" 
*explosion shoots zombie upwards to finish me off* 
 
fuck single player

Tunneled down in a straight line, dug into a pit of lava and died horribly.
 
went back to shaft, fell back down, died again, began crying.

" the holocaust "

" Tunneled down in a straight line, dug into a pit of lava and died horribly.  went back to shaft, fell back down, died again, began crying. "

Can't tell you how many times I've been in a cave system, seen some iron, dug downwards and either fell in to a pit of skellies or just died in lava.
 
On a funnier note one time I tried to break my fall off a cliff by landing on a pig. He survived, I didn't.