That's not what your mom said last night 

Just about. The greatest comeback to anything. Used mainly when talking about the size of genitals, but can apply to anything else.

Person A - Hey look at our science. That's bigger than yours!
Person B - That's not what your mom said last night!
Person C - Oh BURN.

That's not what your mom said last night by More Awesome Than Thou November 13, 2005

That's Not What Your Mom Said in Bed Last Night 

A comeback that people say when someone says, " I bet you are terrible at sex." Or other comebacks. Then that person would come back and say, " That's not what your Mom said in bed last night."

Guy #1: Your dick is probably the size of half of a raisin.
Guy#2: That's not what your Mom said in bed last night.

That's Not What Your Mom Said in Bed Last Night by jazmine1 April 19, 2018