No ALIEN lady ever told Captain Kirk,
"Hey, get your thing out of my nose."
The Big Bang Theory Season 1, Episode 13
[IN ALIEN LANGUAGE]
The Big Bang Theory Season 8, Episode 21
...discover our weaknesses,
and report back to your ALIEN overlords.
The Big Bang Theory Season 3, Episode 15
They exist in case we ever make contact
with an ALIEN civilization.
The Big Bang Theory Season 9, Episode 10
There was no ALIEN.
[chuckles]
The Big Bang Theory Season 12, Episode 18