A turn of phrase generally used by people who feel the need to comment on something and yet at the same time have absolutely NO idea what they just read but would like to come off as intelligent.
Poster: “We felt we were doomed to die and say how powerless we were to help ourselves; but that was good, for then we put everything into the hands of God, who alone could save us.” II Corinthians 1:9

Comment from someone: That's deep
by Electric Nerd February 10, 2010
When bae says something and he/she hits the nail on the head.
bae: Every Charizard once was a Charmander.

me: That's deep.
by Ya Momma Ya Momma Ya Momma April 16, 2016
The situation at hand does not require such desperate actions or "stop being so dramatic"
Person A: I'm going to die if I don't get tickets to see one direction!
Person B: It's not that deep
by ronnie246 May 24, 2014
When someone thinks something means more than it does ,or overthinks it
What if he didn’t text me back because he doesn’t love me anymore”

Man stop deeping it ,he probably just hasn’t seen your text yet”
by Uptown_blues July 22, 2019