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

Before that, I was in college,
and before that I was in the FIFTH grade.
The Big Bang Theory Season 1, Episode 4

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

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

Oh, not just date night.
Our FIFTH anniversary.
The Big Bang Theory Season 8, Episode 24