Had a gunslinger in Hammer Station who simply kept pulling ahead of the tank (me on a VG). The first time we wiped and I told him to knock it off, but unfortunately some people aren't too bright. I told everyone else to basically stand there and laugh if he pulled that stunt again (and we did )
Some guildies of mine apparently ended up in a Coli where only two guys were on the turrets in the first phase. How do people fail that again?
EDIT: Oh, oh! How about the Sin tank who insisted on dropping a sin's shelter on himself during the Prophet fight in Athiss? Made it $%#@ing impossible to see the purple dots - I think only one guy stayed standing for the entire fight that time.