There was definitely some monkey business going on behind the scenes of the Friends set.
During the show's reunion special, David Schwimmer revealed that he didn't particularly enjoy working with his primate pal, Marcel.
David explained that while he was "an animal lover," the monkey would often mess up scenes when it didn't hit its mark correctly.
He also noted that he wasn't a fan of how the monkey's trainer would feed it live grubs in between takes as it sat on his shoulder.
It turns out that the monkey's trainer, Mike Morris, wasn't exactly a fan of David's comments about working with the animal on set — and thinks that David was actually jealous of the monkey.
"David was fine with the monkeys for the first couple of episodes and happy to be there. But people would laugh at the monkey, and I think he got jealous because it wasn’t him getting the laughs," Mike told the Sun.
He continued, "He seemed to get a little bitter about them being there after that. And of course the monkeys didn’t like working with him after he turned on them."
Mike also revealed that David would not rehearse with the monkey, making filming much more difficult because things wouldn't be the same.
He added that he thought it was actually David who threw the monkeys off because he failed to improvise with the animal.
"It made it harder to do the work — a five-camera show is hard to work on with animals anyway, so if you have an actor that’s not very helpful, it makes it even worse," Mike noted.
"It got to the point where he just really resented the monkey being there, he obviously had a problem with her, and he’s still talking about it now...It’s kind of bad that he is still talking about the monkey this many years after the show ended," Mike concluded.
As for the monkeys? Mike says they definitely don't hold a grudge against David and would work with him again.