I wouldn't call it bullying. It was more like light teasing and ridicule.
Anyway, there was this kid in junior high who was quite poor. He never looked like he was freshly showered (and I think the PE teacher let him shower at school), he didn't have much food, low self-esteem, etc, etc. I think he smelled a bit as well.
He was sort of the school misfit and everyone laughed or giggled or made little remarks behind his back. I took part in it somewhat, and I certainly didn't try to stop the kids from laughing or making jokes about the poor guy. It was pretty much mental cruelty.
Many years later I found him on Facebook and apologized for participating in making his life at that time more difficult that it should have been. He didn't reply, but I said my peace.
I have also been bullied. Maybe it was karma.