
It's a non-optional social CONVENTION.
The Big Bang Theory Season 1, Episode 16

No, it's the accepted CONVENTION.
The Big Bang Theory Season 2, Episode 21

Did you tell them that
you're holding your CONVENTION
The Big Bang Theory Season 7, Episode 14

Let's see, the magic store,
the Doctor Who CONVENTION,
The Big Bang Theory Season 10, Episode 19

Try telling him
it's a non-optional social CONVENTION.
The Big Bang Theory Season 1, Episode 16