"Or you'll be thrown off the set."
Jessica Alba says she had a unique rule to follow while filming her guest appearances on the original "Beverly Hills, 90210" show back in 1998.
During a scorching episode of "Hot Ones," the "Honey" actress, 39, detailed her experience playing a pregnant teen named Leanne in two episodes of the hit high school drama.
"On the set of '90210,' I couldn't even make eye contact with any of the cast members, which was really strange when you're, like, trying to do a scene with them," the mother-of-three confessed.
"Yeah, it was like, 'You're not allowed to make eye contact with any one of the cast members or you'll be thrown off the set.'"
The "Fantastic Four" star was only 17 when she appeared on the 8th season of the show, which at the time starred Jennie Garth, Ian Ziering, Brian Austin Green, Tori Spelling, Jason Priestley and Tiffani Thiessen.
Not all the original cast members were still part of the show during Alba's short tenure, including Shannen Dohert, Luke Perry and Gabrielle Carteris.
The series, which ran from 1990 to 2000, was a ratings juggernaut for Fox and ended up being rebooted by the CW network as "90210" in 2008.
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Much of the original cast reunited last year for the latest reboot, "BH90210," which was a quasi-reality show take on the series.
Meanwhile, on "Hot Ones," Alba also dished on her favorite anecdotes about Snoop Dogg, the grueling stunt work on "Dark Angel", visiting the SpaceX headquarters, and drinking Hpnotiq and Hennessy while filming "Honey."
Check out the full episode above!