Friendly fire isn't.
This. Period. If a swing hits, take it, whether it was from a tough opponent, a noob, a teammate, or yourself.
We have been known to frequently commit suicide during a meat grinder for captains in order to make the new guys do it.
A great way to circumvent this that I learned at the Byzantium Opener. Instead of playing "last two standing" as captains, play "first to die and last to die" The confusion is extremely funny when people don't really realize how it works.
Also, I hate it when people kill themselves or "commit seppuku" when they are alone against tough odds. I thought it was cool when I was new, now I just make sure I mutilate the corpses of those that do it. (just making sure, ya know, they mighta called light)