AceShowbiz - Rap mogul P. Diddy pulled the ultimate prank on his "Get Him to the Greek" co-star Jonah Hill during a night out in Los Angeles - by convincing him he had a loaded gun on his person as they sped along Sunset Boulevard in the actor's car.

The "Superbad" star thought it would be fun to hang out with the party king, but soon learned to be careful what you wish for as Diddy took over. Hill says, "He called shotgun in my car, so I'm driving down the street... he's drinking a bottle of vodka and then he puts his foot down on the gas level... We're going, like, 100 miles an hour, swerves the car into the other lane and then goes, 'Have you ever driven with a loaded gun in the car?' I'm, like, freaked out... I'm scared of Diddy."

Hill admits his new pal kept the gag going for weeks and only recently revealed the whole thing was a set up. He adds, "He tells me the other day... 'I was totally messing with you, man!' That was water in the (vodka) bottle, there was no gun in the car. He was doing it totally as a joke... It's, like, 'Wow, Diddy's actually hilarious'."