A stunned audience member wrote on twitter: "OMFG SOMEONE JUST THREW THEIR THONG ON STAGE AND MILEY PUT IT IN HER MOUTH!!!! (sic)"
The singer's wild antics didn't stop there and at another point in the show she straddled one of her female backing dancers, and writhed around her, wearing a bright red fluffy waistcoat.
The "Bangerz" Tour kicked off in Vancouver, Canada on February 14, and features a number of surreal moments including Miley riding a giant hot dog, rubbing her crotch and sucking on a foam finger, as well as plenty of her signature moves—sticking out her tongue and "twerking," the butt-shaking dance move she popularized last year.
Despite the controversies, Miley, 21, has said she wants the show to be "educational" for children.
She said: "I hope people open their minds and they look at my tour as something that I do feel is educational for kids.
"Because I think a lot of people aren't exposed to art enough and that's something that I had to learn about... they pretty much teach you everything in the world as black and white and I want my fans to walk away knowing more about the art that inspires me."