SUM/SYM

SUM/SYM: Shut ur mouth/ Shut your mouth

Definition : SUM/SYM : To not speak when its not required; when you have nothing to contribute productively, you should SYM/SUM and not talk for the sake of talking.
SUM means to ask someone to shut up when they have inappropriate things to say

STM

STM: Shut their mouths.

It’s none of their business to talk about my life; ask them to STM