Ur Mom

Ur mom is a great comeback for anything and everything.
Pumpkinly: S'up.
Gus Fritos the bus seat: Your mom. OHHHHH GET ROASSTTEEDDD OHHHHH

Sometimes it doesn't even need to be a comeback. It can also be a respected formal greeting.
Saratoga: Your mom. OHHHH GET ROASSTTEEEDDD OHHHHHHH OH MY GOSH
Josh: You're literally stupid.
Saratoga: You're just jealous of me!!
Josh: Can you just shut up?
Saratoga: I know you are but what am I?!!

Clearly, Saratoga won that argument. Ur mom is a very powerful phrase that can easily change lives for the better or for the worse. Great power comes with great responsibility. Remember, always be swag and never be a drag. Your mom. Get roasted. OHHHHH

Some more examples for those of you who are slower learners:

Gru- I got an 100% on my test today.
Idiot 1234- I got a 94%
Gru- Haha, stupid.
Idiot 1234- YOUR MOM.
(Gru starts crying in a corner.)

Another example:

Snaps- I think your hot, 4.
4- Awww... thanks... :)
Noah's- You kind of are...
Mullet- I think she is incredibly ugly.
4- You know what? I'm done with you mullet. You should go hitchhike back to your house and cut off your mullet while you're at it. No one freaking likes it! So, leave us now.
Mullet- Fine, I will. Not like you all would care, anyways. You won't even say goodbye!!
4- Oh, yes we will! (Deviously grins) Everyone, snaps for Noah's mullet!
Snaps- I thought it was snaps for Everrett!
4- Oh, shut up.
Noah's- Yeah Snaps, shut up! Ha!
Snaps- Oh yeah?
Noah's- Yeah.
Snaps- YOUR MOM! OHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
4- You just got roasted really bad.
Snaps- Yeah, well, at least he didn't say Eli-i-dus...
Noah's- True, and at least your name isn't Mrs. or Mr. sklisosoislsiosksoisosidoisoisolsiosijklsisisli.
4- Your hair doesn't look electrocuted, either!

(And the three continued to snap for Noah's Mullet into the sunset.)

Heatwarming story, right? Now you know the meaning of your mom, so, YOUR MOM!