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

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

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

I study the brain, the organ responsible
for Beethoven's "Fifth Symphony."
The Big Bang Theory Season 4, Episode 24

but I spent most of FIFTH grade
with my head in a toilet.
The Big Bang Theory Season 7, Episode 2