Ashton Kutcher has given up "punking" his co-stars, because he is scared it will cost him future acting roles.

Kutcher produced and starred in hit 2003 Mtv series Punk'd, playing gags on the likes of Justin Timberlake and Frankie Muniz.

But he has decided to play it straight on-set, so he doesn't alienate himself from all of Hollywood.

He says, "You punk your co-stars (and) people won't want to work with you anymore. So I kind of had to lay off of that."

And Diaz was glad to hear the actor has changed his ways, explaining, "He's figured that out because the biggest thing when you're doing a partnership like this is trust and if you don't trust the person, if you think around every corner you're going to get slapped in the face, it's not so fresh."