Katy Perry and the Rolling Stones? Um, yes! Perry joined the rock legends onstage in Las Vegas on Saturday, May 11 at the MGM Grand as part of their 50 & Counting tour.

Perry performed the 1978 hit 'Beast of Burden' with Mick Jagger and the boys, and she was totally into it, so much so that she couldn't issue a grammatically correct tweet after the fact. We don't blame her -- she had just done her thang with rock icons and adrenaline was surging. Who cares about speaking proper English?

While it's likely that most of the Stones fans aren't big Perry diehards, she worked it and probably won lots of 'em over, looking sexy in a black bustier, short skirt and black boots.

She had great physical chemistry with ol' Mick, dancing with him, singing to him and shaking her hips with him. The strategy was smart, since she comes from a different genre and generation and she was in enemy territory, for lack of a better term.

Below is the transmission of questionable grammatical construction, where Perry tweeted her excitement about bumping and grinding with Jagger.