Bullying will never stop, therefore it's up to the person being bullied to stand up and fight back.
Honestly, I used to always get bullied. People would talk mad trash to me, make fun of me, etc. One day I came home crying, and my Dad got mad at me and told me I should fight them. So I did, and they never bothered me again.
On the flip side, I've seen people get bullied and then commit suicide from bullying.
If you bully people for the sheer fun of it, you should stop.
Also, to the op, if you see someone being bullied, you should stop it.