Now to tell you about
the Theoretical Physics Department...
The Big Bang Theory Season 2, Episode 6
Theoretical physicists do not get canned.
The Big Bang Theory Season 1, Episode 4
Is it maybe because, like Sheldon's work,
your sex life is also THEORETICAL?
The Big Bang Theory Season 6, Episode 9
So now let's bring out THEORETICAL physicist,
Dr. Sheldon Cooper!
The Big Bang Theory Season 6, Episode 18
She's a neurobiologist, and
I'm a THEORETICAL physicist.
The Big Bang Theory Season 7, Episode 21