Yeah, he's writing it on
a NAPKIN like in the movies.
The Big Bang Theory Season 12, Episode 17
Oh, damn it. Can I have a NAPKIN?
The Big Bang Theory Season 3, Episode 5
Ask him for a NAPKIN, I dare you.
The Big Bang Theory Season 1, Episode 2
The famous NAPKIN
The Big Bang Theory Season 12, Episode 24
Good luck. That's the face NAPKIN.
The Big Bang Theory Season 3, Episode 5