The Ocean's Eleven star, who is currently in Germany preparing to shoot new movie The Monuments Men, had been enjoying a meal at the Grill Royal on Friday (25Jan13) when he discreetly picked up a stranger's $134.66 (£84.16) cheque.
Shocked by the generous gesture, the unidentified patron left his business card at the actor's table in the hopes of one day being able to return the favour - only to later realise the man was Hollywood star Clooney.
Afterwards he spoke to local newspaper Bild to ease the Oscar winner's conscience, insisting the 51 year old and his pals had been no trouble at all.
He is quoted as saying, "That's not true at all. They had behaved in a very cultivated manner. I was stunned."