
...and glued a big-eyed rubber ALIEN mask
to the outside of my window.
The Big Bang Theory Season 6, Episode 2

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

I may be an ALIEN, but I have urges.
The Big Bang Theory Season 8, Episode 8

finds proof of ALIEN life.'
The Big Bang Theory Season 12, Episode 20

...he's allergic to Earth nuts,
but I'm the ALIEN.
The Big Bang Theory Season 8, Episode 21