WTF?  Britney Spears and Mel Gibson are vacationing together.

The Apocalypto odd couple are off to Gibson’s Costa Rica home where they’ll be chilling with Spears’ dad Jamie and Gibson’s wife, Robin.

This isn’t the first time the dyspeptic duo have hung outr.  In March they were spotted dining at famed Hollywood restaurant Romanov’s.

Both Gibson and Spears were neighbors when Brit previously lived in Malibu.

"Mel and his wife Robin clearly saw a woman in crisis and wanted to extend themselves in any way possible," a source told People Magazine.

"It’s simply an act of human kindness."   

Or maybe Mel’s just casting his next epic?