Ohhhh wait you were asking what "outting someone" means? It's used in lgbt+ community. When u tell someone ur orientation/gender identity that differs from the "established norm" it's called "coming out." So then when someone does it TO you without permission, basically exposing you, it's called "outting" and could lead to a really dangerous situation for the "outted" party.

What did mokyeon mean by "so you gonna out me too?"