The former Culture Club front man, whose real name is George Alan O'Dowd, has been better known in recent years for his battle with drug addiction and various brushes with the law than he has been for making music.
The Sun said Wednesday he became enraged after a chatty woman distracted him as he was performing at the fundraiser at the Embassy club.
"Why don't you shut the (expletive) up, you rude (expletive!)" the newspaper quoted the 49-year-old singer as telling the woman before he dumped the contents of a glass on her from the stage.
"He wasn't playing his hits, and people were losing interest. It was a shocking lapse of judgment, because people had paid to support the trust," a club source told The Sun.
Video footage of the incident is making the rounds on the Internet.