that's what your mouth says
A way to tell someone you don't believe them, or to say they're full of shit.
John: " Dude, did you know you can actually drink air?"
Jeph:" Yeah right!"
John: "No, seriously! I saw a thing about it!"
Jeph:" That's what your mouth says dude."
Jeph:" Yeah right!"
John: "No, seriously! I saw a thing about it!"
Jeph:" That's what your mouth says dude."