It said right there on the invitation,
"Buckle up for fun!"
The Big Bang Theory Season 10, Episode 19
Well, then, BUCKLE up.
You're in for a cranky night.
The Big Bang Theory Season 8, Episode 20
It's a light saber
belt BUCKLE.
The Big Bang Theory Season 12, Episode 24
Ooh, look, a new Batman belt BUCKLE.
The Big Bang Theory Season 2, Episode 20
the National Belt Buckle Collectors
meet-and-greet.
The Big Bang Theory Season 10, Episode 19