Decked out in a booby-baring costume, with plastic vagina, Miley Cyrus joined forces with PETA spokesperson Pam Anderson on stage at her Dead Petz concert in LA, on Saturday night, to call for an end to whales being held in captivity. But of course!

Miley also donned a prosthetic penis at one point and dressed as a stick of butter. Her stage show appears to be heavily influenced by pal Jeff Beacher's Madhouse show which Miley attended frequently during its run at the Roosevelt Hotel in Hollywood -- where midgets, drag queens and burlesque dancers were the order of the day.

Miley's latest single is called "BB talk" on her fifth studio album, Miley Cyrus and Her Dead Petz, featuring Flaming Lips singer Wayne Coyne -- Cyrus' BFF.

It makes perfect sense that Miley would promote a cause during her performance and even more sense that she'd do it topless and with the former Baywatch babe. But hey, more power to 'em! (Click on the gallery below to see the NSFW pix!)