The `S&M` hitmaker allegedly angered security guards at Stringfellows in London during a visit with her ex-boyfriend Matt Kemp on Wednesday (12.10.11) because she couldn`t keep her hands off the topless performers and even put her head between one of the dancers` legs. A source told The Sun newspaper: "Rihanna couldn`t resist paying for a dance and loved watching the girls in action. But the guards weren`t happy as she was repeatedly touching them, ignoring all the warnings. "At one point she thrust her head between the legs of one of the dancers." The 23-year-old pop superstar and the baseball player partied until 2am in a private booth, where they were joined by celebrity hairdresser Adee Phelan and retired world heavyweight champion boxer David Haye. Earlier in the night, Rihanna - who was named Esquire`s Sexiest Woman Alive 2011 earlier this week - sang Guns N` Roses songs at the Nove Karaoke Bar in London`s West End. The sexy singer - who is in the UK on tour - went to the bar with several of her staff to celebrate a crew member`s birthday and she treated the party to beers and vodka shots and food including pizza and garlic bread. Rihanna couldn`t stop grabbing the microphone and also performed renditions of her own tracks and Kings of Leon`s `Sex on Fire`.