Similar to saying "look who's
talking!"; a comeback for when somebody says or insults
something or somebody, but the statement is
hypocritical
Clark - "Hey
Neil! You're so stupid!"
Neil - "Says you! You're the one with an F in
Math!"
Bob - "Wow! This paragraph is the mos sloppy thing I have seen!"
Mark - "Says you! All you wrote about was how 2+2 is equal to 5!"