Brit to Ellen: Rap It Up Already

12/16/2008 11:05 AM PST BY TMZ STAFF
Britney Spears and Ellen recently went Christmas caroling -- but these definitely weren't your grandma's carols.

Britney Spears & Ellen: Click to watch
In an "Ellen" episode airing today, not only does DeGeneres get a lesson in booty shaking from a shockingly sane and funny Spears, the two also do a freestyle "Jingle Bells" rap ... in costume.