Denise Truscello, WireImage

Avril Lavigne and Nickelback rocker Chad Kroeger's surprise engagement back in August has become the inspiration for some amazing Halloween couples costumes this year. But the award for best "Chavril" costume goes to the Canadian songstress' very own ex-husband, Deryck Whibley!

Oh yes he did! The Sum 41 rocker slapped on a pink-and-green-streaked blonde wig and signature Avril hoodie, and impersonated his ex-wife at a Halloween party. A pal of Deryck's took on Chad, wearing a Jack Daniels printed T-shirt, platinum wig and faux facial hair. The two posed for an amazing photo, which has made it's way onto perezhilton.com.

See the photo here!