The theory is that
if you really tax your BRAIN,
The Big Bang Theory Season 10, Episode 22
Yeah, I'd love to see
a scan of your BRAIN sometime.
The Big Bang Theory Season 2, Episode 15
Think about it with your BRAIN,
and then say it with your mouth.
The Big Bang Theory Season 12, Episode 7
...to exercise our minds
with BRAIN teasers like that.
The Big Bang Theory Season 2, Episode 5
My BRAIN and I are best friends,
it should tell me everything.
The Big Bang Theory Season 10, Episode 18