my favorite is when people do share an interest, but not in the same way.
i like gaming and cycling... but a lot of gamers and cyclists are hyper territorial about their specific genre they like, and think other genres are stupid/wrong/bad. i play a variety of games, and it never fails that someone hones in on that I played COD (I must be a fake gamer dude bro), or a JRPG (I must be an anime nerd) and then makes a massive generalization based on that one game I played. I also have like 6 bikes and do lots of different kinds of riding and people fixate on the one they don't like or have stupid stereotypes about and then get really accusatory about it. like owning a road bikes makes me one stereotype, owning a DH bike makes me another, and then they get super double mad at you for because they often regard these as contradictory boxes, only one of which you must fit in.
Shit is so weird. they also do it with identity now. I'm so sick of being told what I have to enjoy/not enjoy because of my skin color or my sex. i love to cook and clean and keep my place neat, but most women I meet think it means I'm latently homosexual because of that because in their mind straight men can't cook or clean, only gay men can.