could be evidence
of ALIEN civilization.
The Big Bang Theory Season 12, Episode 20
He was only pretending to be scared to trick the ALIEN king.
The Big Bang Theory Season 12, Episode 18
Okay, here's a question.
As an ALIEN pretending to be human...
The Big Bang Theory Season 8, Episode 8
...who's been replaced with an ALIEN pod.
The Big Bang Theory Season 2, Episode 6
They exist in case we ever make contact
with an ALIEN civilization.
The Big Bang Theory Season 9, Episode 10