Not generally, although mostly because I play TF2. Halo over my friends house is another story. I'm not sure if its technically team killing, but if we get split up, I tend to knock out enemy shields so my friend can get the kill. Although one memorable moment was Halo 2, team rockets. We had just played a bunch of matches on red team. This match we were on blue, however I didn't pay attention. The match starts, I yell , "Shit I spawned in the wrong base" and shot. I'm booted within 2 seconds. You can probably guess which base I actually spawned in.