I died by a hard scope then when i respawned i literally never actually lived because the guy was spamming his tac knife button and messing around while walking and I spawned in his knife. Then when i respawned i got stuck by a random semtex..... I think i died a little bit inside while this happened to me...
Was over at friend's house and another mutual friend came over. He normally played PS3 MW2 and we were on the 360. First game he went to was an S&D on Karachi, hadn't spawned yet due to him adjusting sensitivity and control layout. "Let's do this," he says, hits spawn and gets hit by a noobtube from across the map immediately. Funniest thing I've seen happen to a friend of mine. That minute of complete confusion on his face... Totally priceless.
Way too many to remember the worst so I'll give you my most recent.
Domination. Nuketown. Kid on other team is camping his left side with a Target Finder and LMG and just holding down the trigger. I die on MY left side of the map and spawn right in front of this ass hat. Instant death. Spawn in the exact same spot, instant death. Spawn a third time 3 feet behind my two dead bodies, this kid is still holding down the trigger, third instant death. Ragequit.