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She's ready to take it all off -- just be a generous tipper!

Cameron Diaz headed to a pal's Halloween bash in Beverly Hills on Friday night. Her costume for the masquerade party? A stripper!

Sadly, the sexy Bad Teacher actress, 39, probably didn't win any costume prizes that night.

Perhaps assembled last-minute, Diaz's ensemble consisted of skintight leather pants, boots, a cleavage-baring black top and blazer. The tell-tale stripper props? A sexy belly chain -- and plenty of dollar bills tucked into her waist!

Diaz has been keeping a fairly low profile since she and Yankees slugger Alex Rodriguez finally ended their on-and-off romance in mid-September.

"She's very busy with her career," a source told Us Weekly. "They're still very friendly and like each other."

Tell Us: Should Diaz have made more of an effort with her costume? What costume should she try next?