this verbal warning and boundary is provided when someone takes personal offense to what someone else is saying. It is meant to urge the person to reconsider what they are saying.

The term can be followed up with an “or else” but it is usually the final warning before a consequence is given (a slap, getting blocked, etc.)

Watch out for danger behind your back (like you might get jumped or something).

Watch your back.

Keep an extra set of eyes on the back of your head.

The thing stupid people say to someone that curses. Referenced in one of jacks film's videos

Watch what you're saying bro

T. slang that means relax and shut up

synonym for "nize it"

To watch your behind, used in aviation as a warning by your wingmen.

This phrase simply means that you should watch what you are saying because the person saying this to you will most likely knock your teeth out of your oral cavity because they are not liking what you are saying.

A phrase that is said when one has purchased a bag of peanuts before going down a ski lift, and is waiting for the safety bar to lower, that warns them to protect their bag of peanuts.