
I guess we wait until they're old enough
and let them choose their own THEORY.
The Big Bang Theory Season 2, Episode 2

When I entered the field of string THEORY,
I was a prodigy.
The Big Bang Theory Season 8, Episode 6

NARRATOR:
Previously on The Big Bang Theory:
The Big Bang Theory Season 6, Episode 1

You mean have a funeral
for our THEORY?
The Big Bang Theory Season 12, Episode 10