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Talk about a full frontal facepalm. Lady Gaga fancies herself a performance artist, so it's not too surprising to hear news of the pop star doing something crazy in the name of art. But performing completely naked on stage? That's a new one… even for Gaga.

Mother Monster performed a surprise set at London nightclub G-A-Y this past weekend. Singing her new song "Venus," Gaga started the show dressed up as a ghost… but soon after stripped down to just her birthday suit.

SODAHEAD SLIDESHOW: Most R-rated music performances of all time

Comedian Matt Lucas tweeted after the show: "Just saw Lady Gaga do a surprise set at G-A-Y... All agreed it was impressive but we're staying gay." Fair enough.

Gaga's performance was definitely racy, but is it the most R-rated on-stage performance of all time?

We all remember Miley's risque performance at the MTV VMAs, when the twerking pop star rubbed a foam finger all over herself.

Then, there was the time Justin Timberlake ripped off Janet Jackson's top on stage, exposing Ms. Jackson to millions of viewers during the Super Bowl Halftime show back in 2004.

And let's not forget the moment when Madonna and Britney Spears shared an open-mouth kiss at the end of their MTV VMA performance in 2003. Tame for now, but pretty risque for 10 years ago...

From Gaga to Miley to Madonna, who's had the most R-rated musical performance of all time?