Hollywood is gearing up to mix it up for the holidays in a fun new ad campaign for Gap. Stars like Mila Kunis — whose “Hang Up Your Own Stockings” ad debuts exclusively above — Jennifer Hudson, Ashanti, Mary-Louise Parker, Jason Bateman and more stars will appear wearing a mix of the brand’s latest collection of knitwear and other fashion must-haves. But our favorite part of the campaign has to be Gap’s Merry Mix It site, which launches today and features a series of webisodes with unexpected pairings of actors, musicians and comedians performing remixed holiday carols. The unique site allows you to watch them perform or get in on the action by remixing and downloading your own version of “Jingle Bells,” recorded by Flo Rida and Trey Songs, using clips from the entire Gap Holiday cast — which includes everyone from Selma Blair to Jason Biggs to the Dixie Chicks and members of SNL. Click here to check out the site.