In the first Halo (Original Xbox, y'know.. in PERSON co-op) on the first map(?) me and my friend were on our 3rd playthrough (this time on legendary) and while we were crossing the bridge I attempted to jump up n' down while running across.. and accidentally hit my bash button killing my friend (who was in front of me) and all he could say was "MY PISTOL!"
That same day on a flood level during a rather hectic point I toss a plasma grenade and my friend being who he is runs into it while being completely oblivious to this fact.
Me: "Whoops."
Friend: "Whoops?" *BOOM* "Fu*ker."