♪ The Earth began to COOL
The Big Bang Theory Season 12, Episode 3
Stop trying to be the COOL dad.
The Big Bang Theory Season 10, Episode 1
Hey, guys, what are you--
Oh, that's here, COOL.
The Big Bang Theory Season 10, Episode 10
-that is so COOL.
- LEONARD: Oh.
The Big Bang Theory Season 10, Episode 22
Cool.
The Big Bang Theory Season 5, Episode 7