
A semi-truck might be an ALIEN robot...
The Big Bang Theory Season 6, Episode 2

I thought you were gonna be an ALIEN.
The Big Bang Theory Season 8, Episode 8

They exist in case we ever make contact
with an ALIEN civilization.
The Big Bang Theory Season 9, Episode 10

Okay, here's a question.
As an ALIEN pretending to be human...
The Big Bang Theory Season 8, Episode 8

No ALIEN lady ever told Captain Kirk,
"Hey, get your thing out of my nose."
The Big Bang Theory Season 1, Episode 13