Computers.
Not even computer games, although that would have added bonus points as a target for bullying, but using a computer in general.

Then again, bullying was more of an attitude thing during my youth, so you didn’t get bullied for you hobbies, but for your behavior.
Ugly geeky kids were left alone if they hung out with other geeky kids. They got bullied as soon as they tried to associate themselves with the cool kids.

That took me a while to think about.