A MAN cut off his own penis with a large knife in front of diners at a busy London restaurant. Witness Stuart McMahon, who was eating at Zizzi in the Strand with his girlfriend on Sunday, told the Sun: "This guy came running in then charged into the kitchen, got a massive knife and started waving it about. "Everyone was screaming and running out as he jumped on a table, dropped his trousers and popped his penis out. "Then he cut it off. I couldn't believe it." Police said a man in his 30s was taken to a south London hospital where his condition was stable today.