
...and if I can figure out a way to do so
and sound SINCERE, I will.
The Big Bang Theory Season 4, Episode 9

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

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

Okay. Now, see you look SINCERE
but your words are completely false.
The Big Bang Theory Season 10, Episode 6