
...because he said
it was a THEORETICAL nut conflict.
The Big Bang Theory Season 8, Episode 21

Is it maybe because, like Sheldon's work,
your sex life is also THEORETICAL?
The Big Bang Theory Season 6, Episode 9

Of course not.
I'm a THEORETICAL physicist.
The Big Bang Theory Season 2, Episode 23

What would a THEORETICAL physicist
understand about an experiment anyway?
The Big Bang Theory Season 10, Episode 4

You're summa cum laude in THEORETICAL
physics from Stanford University.
The Big Bang Theory Season 6, Episode 3