While we're all waiting to see if Rebirth ever actually gets released, Lil Wayne went off and recorded "Revolver," a track from Madonna's upcoming greatest hits album Celebration. The song, which has leaked in about a half dozen forms, this one allegedly being the "finished" version, is centered around some Britney Spears-esque Auto-Tune work from Madonna and a pretty cheesy gun metaphor. Wayne does a mailed-in verse, the kind of which he's been doing for about the last eight months, and joins Madonna on the last chorus. This won't make anyone wish for an album-length collabo, that's for sure.

Celebration is due out on Sept. 29. [Idolator]