Louis Tomlison doesn't mind Harry Styles playing pranks on him

One Direction's Harry Styles is one seriously cheeky chappy.

Flashing his bum in the recording studio is just one of 17-year-old Harry's pranks.

Harry likes to pull his trousers down,' says Louis Tomlinson, 20. He's always getting his bum out.

I've been asleep before and Harry has hit me round the head with his penis.

It actually wrapped around my whole face - who wouldn't be envious of that?'

It's not just Harry who likes to wind his buddies up - the whole band are practical jokers.

This lot think it's funny to come into my room and spray me in the face with a fire extinguisher,' One Direction's Niall Horan, 18, tells Celebs On Sunday.

When I was on the loo, they'd all come in and take pictures of me.'

SEE EXCLUSIVE VIDEO Teen Now meets One Direction>>

SEE PICTURES One Direction perform with JLS on The X Factor>> 

SEE VIDEO One Direction mobbed by screaming fans in London>>