Blue, as in DEPRESSED.
The Big Bang Theory Season 4, Episode 22
It's Christmastime and
Jimmy Stewart's really DEPRESSED
The Big Bang Theory Season 7, Episode 11
...green is jealous
and blue is DEPRESSED.
The Big Bang Theory Season 4, Episode 22
Has he been DEPRESSED?
Breaking Bad Season 2, Episode 2
...because I'm fun,
I'm not clinically DEPRESSED at all.
The Big Bang Theory Season 6, Episode 5