Pop star Miley Cyrus shocked fans at the opening night of her new tour by taking to the stage wearing fake breasts and a prosthetic penis.

The Wrecking Ball singer kicked off the first date of her Milky Milky Milk Tour in Chicago, Illinois on Thursday night (19Nov15) to promote her latest album Miley Cyrus & Her Dead Petz.

Miley ramped up the theatrics for her debut show at Chicago's Riviera Theater and stunned the audience by performing in a skimpy costume complete with prosthetic breasts and a strap-on plastic penis.

Pictures show the singer taking to the stage wearing a purple wig with a unicorn horn and a large baggy shirt, before she stripped off to reveal her controversial costume.

She performed hits such as We Can't Stop and Dooo It! along with her new material on the first show of the tour, which features eight stops in cities across the U.S. and Canada.

The tour, which will reportedly feature appearances by Miley's collaborators The Flaming Lips, concludes in Los Angeles on 19 December (15).