Deryck Whibley and his model girlfriend celebrated Halloween by dressing up as the rocker's ex-wife Avril Lavigne and her new fiance Chad Kroeger for a costume party.

The Sum 41 star donned a blonde wig with colored streaks and heavy eye-make-up to attend the bash as his former partner, while his current girlfriend Ari Cooper dressed as the Nickelback star.

Photographs of the pair show Cooper sporting fake facial hair and a curly wig as Kroeger, while she also holds a cup with his name written on the side.

Lavigne split from Whibley in 2009 and she became engaged to Kroeger earlier this year (12) after a whirlwind romance.