The characters in Friends follow the stereotypical behaviours associated with being either male or female. If any character dares to behave outside the bounds of their assigned gender norms, they're punished, mocked, and assumed to be gay. It's a constant punch line in the show and one that I cannot stand.
Take the whole "Chandler might be gay" narrative. The characters mock him any time Chandler's feminine side surfaces. In season one, all of the "friends" and his coworkers accuse Chandler of "having a quality" of being gay. Monica seems to be Chandler's biggest accuser, bullying him anytime Chandler shows his appreciation for something that is deemed feminine. As a result, Chandler becomes paranoid that his actions aren't masculine enough and checks himself with self-deprecating humour. Maybe Chandler's homophobia is a result of his relationship with his transgender dad (a whole other issue), but whatever it is, I'm not here for it.
Chandler isn't the only character that conforms to gender roles: when Ross's ex-wife gives their child a Barbie, Ross doesn't understand how his son, Ben (Cole and Dylan Sprouse), could enjoy playing with a doll that is stereotypically intended for girls. To combat this, and ultimately get his son to conform to gender norms, Ross forces Ben to play with a G.I. Joe, a "manly" toy. When Joey gets a female roommate, Janine (Elle Macpherson), she begins to redecorate their home. Joey starts to enjoy the new additions to the apartment until Chandler claims that Joey is turning into a girl — I'm sorry, what? — shaming Joey into taking down the decor.