The only kind of meat a priest could eat on Friday was nun.
5 seconds sound clip from the Cheech and Chong's Up in Smoke movie soundboard.
You can hear this line at 00:49:35 in the Blu-ray version of the movie.
Quote context
[...]
- They almost look like real nuns, don't they, Harry?
- Right down to the stockings.
- Not bad.
- You ought to be ashamed of yourself, you know that?
- Reminds me of a funny story my dad used to tell me, Harry.
- The only kind of meat a priest could eat on Friday was nun.
- Inside!
- Harry, get a sample of that car.
- Start the interrogation, Murphy. I'll be right back.
[...]