Megan Fox has mocked Will Arnett's young girlfriends.

Megan Fox

Megan Fox

The 30-year-old actress told her 'Teenage Mutant Ninja Turtles' co-star - who has kids Archie, seven, and Abel, five, with ex-wife Amy Poehler - she was "worried" about his dating habits during shooting of the 2014 movie as she feared the set didn't have the facilities to cater for the 46-year-old star's youthful female companions.

She recalled on 'Conan': "He was sort of dating a lot and every other week there was a new girlfriend and he would bring them to set.

"They were progressively getting younger and younger as the weeks went on, and it got to the point where I was like, 'Buddy, I'm worried. Should I talk to craft service and make sure they have Lunchables for your girlfriend?' There's no food here with cartoon characters on it.' "

Megan also admitted Will is much more "professional" than people might expect.

She said: "Yeah, he's super funny. He's exactly like you would anticipate he is only he's very professional.

"No, I don't mean that in a bad way. You'd think he'd be joking around while we're rolling but he's not. He's focused and doing what we're supposed to do."

Despite her jibes, the pair are friends and Will recently joked he plans to buy the "hippy dippy" brunette beauty - who is expecting her third child with estranged husband Brian Austin Green - a birthing tub.

He said: "She is hippy-dippy. I should buy her Birkenstocks or something or a birthing tub.

"That's what I'm going to get her. It's like a whole tub and they get in it and everyone's in it at the same time...Chanting and all the fluid is happening at once."

A day after it was revealed she was pregnant to a mystery father, Megan - who also has sons Noah, three, and Bodhi, two, with Brian - posted an Instagram collage featuring Will, her 'Transformers' co-star Shia LaBeouf and fellow 'New Girl' cast member Jake Johnson and added the caption "#NotTheFather".