I've just watched the "The Apartment" Episode, and noticed that Ralph is calling Potsie "Warren" at one Point, when he was angry.

Was that the first and last Time he ever did that?

What about the others? Did they ever called Potsie by his real Name -or- was Mrs.C the only one?

I thought maybe Fonzie called him Warren once but i'm not sure. Most of the time they called him Potsie.

Ok. Found another one.

Fonzie is saying "Warren..." when they have a little Talk in Fonz' Office in the "quits school" Episode