I've been bonus-balled on numerous occasions, and sometimes by my own team.
On every occasion it hurt like f**k at the time, and yes, I probably whined like a pig, but when I thought about it, I realised I could have made it more obvious I was out of the game, or just left the field quicker (or by a more sensible route that didn't involve walking through a string of paint coming from a team-mate!)
Either way, the stinging stops after a few minutes and all you get left with is a nice round bruise or two to impress the girls... What's the big deal? It's paintball. If you don't like getting shot, get better, or don't play.