Chad Kroeger vs. Deryck Whibley

Things got messy when Avril Lavigne's ex-husband Deryck Whibley and his current girlfriend switched genders for the night dressed up as Lavigne and her fiance, Nickelback frontman Chad Kroeger.

Things got even messier when Kroeger's sense of self-importance called out Sum 41's Whibley for the costumes on Twitter.

 
This is what the kids call "throwing shade." Or in this case, Nickelback mocking Sum 41. What we're saying is there are no winners here -- only losers.

Whibley's account was suspended shortly after, but has since been reinstated. No word on whether the not-so-important singers have made amends, or if Whibley has taken Kroeger up on his offer of a rousing game of bowling.