In Halo 1 and 2:

-Jumping out of a Warthog driver seat just as my AI counterparts drive off the edge of a cliff due to my acceleration.

-Jumping out of a moving Warthog full of AI counterparts as another full Warthog comes up behind and wasting all of my plasma grenades blowing both up, then watching as the Warthogs and passengers fly in the air and crash into each other.

In general:

-I take great enjoyment in shooting and killing my friends' characters in multiplayer co-op. Usually they get really pissed off, but I'm willing to screw up a whole mission if necessary to shoot at them.

-Another thing I do in most games is save and then purposefully jump off a cliff. I don't know why I do this, but in any game with a cliff I do it at least once to watch my character fall off.