Arnold Schwarzenegger goes undercover to work at a gym

"Stop being a baby. This is not baby gym."

Strongman, action hero and former governer of California Arnold Schwarzenegger dons a (really stupid looking) fake moustache and wig as he goes undercover as a trainer at a local gym

It's all part of Arnie's increasingly madcap efforts to promote awarness of, and raise money for, after-school programs for US kids.

And it's actually quite funny, as Arnie demonstrates a talent for off-the-cuff comedy that we sometimes forget he possesses.

We particularly liked his convincing the woman in the pink top that she had to do '10 reps of water drinking'.

"That's rep number seven," he tells the slightly frightened gym-goer. "STRAIGHTEN YOUR BACK!"

We're guessing that most people rumbled it was him pretty quickly - Arnie's a hard guy not to recognise.