Nelly was arrested on Saturday for allegedly raping a woman on his tour bus.  The woman claims she went to an after-party where she got a little tipsy and was later taken to the bus.  She says she refused to have sex with him, but he forced himself on her . . . and didn’t use protection.

Nelly  claims she’s “completely innocent.”  He was reportedly booked on second degree rape charges . . . but was released without being formally charged.