Wilmer Valderrama had a "friendly rivalry" with Ashton Kutcher on 'That '70s Show'

He penned: "Ashton was far more intelligent in real life than the character he played, and he was far more serious about the craft of acting than it appeared.

"He and I soon developed a friendly rivalry to see who could get the biggest laughs from the audience on the first take."

The pair gave themselves the name "two-takers" as they would "always try to land the first perfectly, then do the second take just for fun."

Wilmer recounted: "If you mess up on the first take and try for a huge laugh on the second, the joke never lands as powerfully. If you need to do a third or fourth take, you might as well forget it."

The 'NCIS' star didn't want to get his "hopes up" when he was auditioning for the role of Fez, because he had already lost a number of acting gigs.

He admitted: "I didn't put much stock into the show at first. I vowed to give it my all, just like everything else. But after you've been auditioning for a few years without much success, you learn not to get your hopes up."

Some of the cast from the show - which ran from 1998 to 2006 - reunited for the spin-off 'That '90s Show', but Wilmer, Ashton and Mila Kunis (Jackie Burkhart) did not return.

Wilmer explained that his schedule was slammed and wished the new cast all the best.

He told PEOPLE: "There's no time!

"We're pushing 20 episodes a season [on NCIS], but at the same time, it's the kids' jobs."

Wilmer added: "This is their show now, and I think it was important that we came and pay respect to their show and have fun with the legacy of what we did.

"At the same time, it was really about, you know, now seeing them take it over."

The Netflix spin-off, which premiered last year, saw Kurtwood Smith and Debra Jo Rupp reprise their roles as Red and Kitty Forman.