There is a Seinfeld episode which contains the following dialogue:
Father-priest: Are you ready my son?
George: Yes faddah.
Father-priest: What did you say?
Father-priest: I thought you said faddah.
George: I said faddah, I meant Father. Just a little bit nervous.
My google search produced the song "Hello Muddah, Hello Faddah" (see here), as well as some hints that it is pidgin English. Is the dialogue funny because faddah is typically used by kids?