He didn't remember me, because the last
time we met I was in a Halloween COSTUME.
The Big Bang Theory Season 2, Episode 14
Except the Halloween COSTUME
The Big Bang Theory Season 7, Episode 2
Yeah, now about those.
They came from a COSTUME shop...
The Big Bang Theory Season 8, Episode 22
Sorry, you're not
wearing a COSTUME.
The Big Bang Theory Season 12, Episode 6
She may have heard about
my cool Dumbledore COSTUME.
The Big Bang Theory Season 10, Episode 17