
and where Leonard got his PhD,
so it may have gone downhill.
The Big Bang Theory Season 10, Episode 24

If you could run out and get a PhD,
that might make her like you.
The Big Bang Theory Season 8, Episode 23

I have a PhD from Cornell University.
The Big Bang Theory Season 6, Episode 22

I must say, Amy, I was very impressed
to see that Bernadette got her PhD.
The Big Bang Theory Season 4, Episode 24

A PowerPoint presentation
by Sheldon Cooper, PhD."
The Big Bang Theory Season 3, Episode 15