I was playing an America's Army LAN game at my school a couple years ago (we had installed it in the computer lab and played LAN games at lunch) and I was in this building defending this one staircase from a couple enemies on the floor below. I was red and bleeding, prone, and I had called for one of my teammates to come help me, and I pulled out a frag intending to bounce it off the far wall to go down the second set of stairs when it bounced up off the handrail, bounced back off the angled roof of the stairwell, and landed right in front of me. At that moment my teammate showed up. Boom.
Another time I was playing defense on that Bridge level and the admin had set the game to everyone only had RPGs. So I take position behind one of the pillars, spot an enemy, and fire, only for the RPG to pull a hard 90 degree turn and kill a teammate.
A bit later our team was down to me and one other guy, there was only one guy left on the enemy team, and my teammate and I were crouched behind this one destroyed car for cover. I saw the last guy, and fired my final rocket, which made a picture-perfect vertical 360 degree loop and impacted right at my feet, killing the 2 of us crouched there.
Even today when I mention that incident we all burst out laughing; I swear that RPG had a guidance system for my teammates...