
I have a PhD in astrophysics.
The Big Bang Theory Season 10, Episode 18

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

and where Leonard got his PhD,
so it may have gone downhill.
The Big Bang Theory Season 10, Episode 23

I'm getting my PhD.
The Big Bang Theory Season 4, Episode 24

Sorry. I didn't get my PhD
in quitting.
The Big Bang Theory Season 11, Episode 15