
Leslie Winkle is the FIFTH girl
I've ever had sex with.
The Big Bang Theory Season 2, Episode 16

I was done with Latin by FIFTH grade.
The Big Bang Theory Season 3, Episode 2

It's more likely that you will spend
your careers teaching FIFTH graders...
The Big Bang Theory Season 2, Episode 6

Uh, well, it's not
May the FIFTH...
The Big Bang Theory Season 7, Episode 22

I think
it's only the FIFTH stage
The Big Bang Theory Season 12, Episode 24