Prince William's buddy Guy Pelly was caught on film puffing on marijuana while partying with a royal entourage in Glos, England.
Pelly and William were dancing with a group of friends at the Tunnel House Inn Saturday night when "a pretty girl" walked over and handed him a joint, The Mirror reported Monday.
As he took a drag of the marijuana, he saw a camera and realized he was set up, friends told the newspaper.
"He feels he's been tricked and has let William down," one friend told The Mirror.
Pelly is a close friend of William's brother, Prince Harry, the newspaper said.