It's the battle of the mediocre musicians as Nickelback front-man -- and Avril Lavigne's fiance -- Chad Kroeger takes on former Sum 41 lead -- and Avril's ex-husband -- Deryck Whibley.

Did you follow all that?

Whibley and his girlfriend dressed up as Lavigne and Kroeger for a Halloween party, posting their gender-swapped and generally unflattering costumes on Twitter. Because nothing says you've moved on quite like mocking your ex and her new man.

It's not the first time Chavril has been publicly ridiculed on the internet, but Kroeger took to Twitter (where intellectual discourse reigns supreme) and retaliated anyway.

There are many definitions of irony, and now we'll add "using your Nickelback account to call someone else a nobody" to the list.

Whibley's Twitter account has since been suspended for unknown reasons, and that's a bummer. However will Avril know he's over her if he can't passively-aggressively tweet about it?