It's based on the PREMISE
The Big Bang Theory Season 7, Episode 3
Based on the PREMISE that
"lumen" sounds like "lemon"?
The Big Bang Theory Season 12, Episode 14
Let's begin with the PREMISE that everything
you've done up to this point is wrong.
The Big Bang Theory Season 2, Episode 18
If you didn't cheer at my entrance,
it's too late to buy into the PREMISE.
The Big Bang Theory Season 3, Episode 4
Well, if we accept your PREMISE and also
accept the highly improbable assumption...
The Big Bang Theory Season 1, Episode 17