
LEONARD: I can't believe you think
he only wears it on Halloween.
The Big Bang Theory Season 4, Episode 24

You know, like how I practiced
for that Halloween haunted house
The Big Bang Theory Season 10, Episode 6

Happy Halloween.
The Big Bang Theory Season 1, Episode 6

On Halloween.
On this couch.
The Big Bang Theory Season 12, Episode 6

A time machine from a science-fiction show
has nothing to do with Halloween.
The Big Bang Theory Season 6, Episode 5