The 49-year-old singer was performing a gig at the Embassy club in Mayfair in London to benefit The Meningitis Trust.
When a woman started talking over him during his act he reportedly got up and said: 'Why don't you shut the f*** up, you rude ****!' He then allegedly poured his drink all over her from the stage.
An onlooker said to UK newspaper The Sun: '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.'