CHICAGO - JOHN C REILLY BECOMES ON-SET PRANKSTER

CHICAGO star JOHN C REILLY took over GEORGE CLOONEY's crown as top Hollywood prankster while he made his upcoming movie CRIMINAL - and co-star DIEGO LUNA was the constant target.

The actor admits that while he filmed the movie, which also stars MAGGIE GYLLENHAAL and opens in America on 10 September (04), he decided to take his naughty antics off the camera.

He says, "Me and Diego Luna really hit it off. I teased him mercilessly through the whole shoot. Something about playing con men makes you feel like constantly tricking each other.

"For most of the movie we're driving this car, a fancy MERCEDES we came across. It had seat warmers in it, and I turned his seat warmer on maybe 50 times. He finally started putting tape over the seat warmer button to stop me."

The situation was especially tough for Luna because they were filming in the midst of a triple-digit heat wave at the time.