Ke$ha's Grossest Moments: Singer Drinks Urine, Eats Beards & More (PHOTOS)

We're not trying to be mean when we say this: Ke$ha might be the grossest pop star ever.

Don't get us wrong, we're all for dancing like no one is watching to her songs, but the self-professed "dirty little sister" of pop music, is often just that -- dirty. In her upcoming MTV documentary series, "Ke$ha: My Crazy Beautiful Life," the 25-year-old singer drinks her own urine. Sure, Ke$ha is "a ballsy motherf**ker, [who is] not afraid of pushing boundaries," but she frequently hurdles over the boundary lines of good taste.

For starters she asked her fans to send her a tooth, and she was able to fashion a bra, headdress and earrings out of the 1,000-plus canines she received. Then we met her "boyfriend," and there's always the time she claimed she had sex with a ghost . We're not exactly sure what happened, but last September the singer told Ryan Seacrest that her album "Warrior" is about "experiences with the supernatural... but in a sexy way."

"I had a couple of experiences with the supernatural. I don't know his name! He was a ghost! I'm very open to it," she explained.

While these are major TMI moments, when it comes to real gross-out incidents, who can forget when she tweeted a photo of herself peeing in the street?

And her all-time stomach-churning stunt has to be her "Put Your Beard In My Mouth" blog , which is exactly what it sounds like: a blog devoted to photos of guys with impressively long beards and Ke$ha putting those beards in her mouth.