There’s never a shortage in on-set celebrity feuds, but normally stars like to keep their mudslinging strictly professional. In other words, you rarely see someone badmouthing their fellow co-star over their acting skills. That’s a bit of a low blow, you know, considering their profession and all.

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But every so often, some famous folk can’t keep their opinions to themselves and must let everyone know how bad an actor their co-star is. The video below takes you through four awkward situations where celebs’ acting abilities were put on check by the same people who worked with them.

Probably one of the biggest on-set feuds is between Will Smith and his The Fresh Prince of Bel-Air co-star Janet Hubert. Janet, who used to play Aunt Viv on the ’90s sitcom, has been very vocal in the press about her hatred for Will. Her animosity is so intense, Will has laughed off her comments in the past.

“No matter what, to her, I’m just the Antichrist,” Will said way back in 1993.

As for what the other Fresh Prince co-stars think of the Will vs. Janet feud? Well, they’re more on Will’s side.

“The b—h was crazy,” co-star Alfonso Ribeiro said in 2009. “She went nuts! Long story short, and there were days when we were all on the set and she would literally go off on people and they got to a point by the time the second season came around where we’re like, ‘This is unacceptable.'”

And don’t hold your breath for a reunion either, because Janet says it’s not going to happen.

“There will never be a reunion,” she told TMZ. “I will never do anything with an a—hole like Will Smith.”

Gee, tell us how you really feel!