don't get beat up
If someone if Annoying you, you tell them "don't get beat up" Meaning Don't mess with you because you'll beat them up
Example:
Bryan told Betsy "haha you're so short" and Betsy replied "shut up Bryan!! Don't get beat up!"
Bryan told Betsy "haha you're so short" and Betsy replied "shut up Bryan!! Don't get beat up!"