Chris Colfer's Bathroom Accident on Monk Set

Glee star Chris Colfer was left red faced after realising he had relieved himself in a prop toilet.

The actor was caught short in the middle of filming and dashed to the nearest lavatory to pee - only to realise the loo wasn't supposed to be used.

The 20-year-old was mortified when he discovered he'd urinated in a prop toilet for U.S. TV series Monk, which stars Tony Shalhoub.

He recalls, "One night we were working really late and I had, like, 27 Diet Cokes and I had to use the restroom really bad... I noticed the toilet wouldn't flush, and the sink wasn't working either. I looked up and realised there was no ceiling, and then I realised, 'Oh my God, I'm on a soundstage. I was on the set of another TV show. I was on the set of Monk."