
A, that was not a joke,
that was a SINCERE request.
The Big Bang Theory Season 6, Episode 24

I sense that's not SINCERE,
although I have no idea why.
The Big Bang Theory Season 3, Episode 11

Not to "Sin City" but to "SINCERE city."
The Big Bang Theory Season 9, Episode 13

Did you make the apology
as SINCERE as I would have?
The Big Bang Theory Season 9, Episode 23

And I want you to know that
that is SINCERE. I do feel bad.
The Big Bang Theory Season 9, Episode 13