I have personally never been bullied. I was always big enough to not worry.
However, my friends weren't so lucky.
They were tormented endlessly until one day i did something.
I calmy explain to the group of 5-6 guys that i was tired of the bullsh!t and if they ever looked at my friends the wrong way again i would grind them into the dust.
I said this with my hands placed firmly around 2 of their throats.
They never messed with my friends again