>>>How about this one? In that same theater:
>>>
>>>- IS THERE A DOCTOR IN THIS THEATER?
>>>
>>>- Yes! I am a doctor.
>>>
>>>- So, doc, how do you like the movie so far?
>>
>>Too much Marx Brothers lately?
>
>Didn't know it was them. Wouldn't expect it either - weren't they supposed to be on the screen and not in the audience?
>
>Came through someone on a forum, equally ignorant of the origins as I am.

In the movie "Horse Feathers" they play football. At one point, Groucho crawls out of a pile up and starts shouting, "Is there a doctor in the house, is there a doctor in the house?". A guy way up in the stands scrambles over people and rushes stumbling and out of breath down to the field and says, "I'm a doctor." Groucho says to him, "How do you like the game, doc?". Granted I'm somewhat paraphrasing because I don't remember it word for word, but that's pretty close. I assume it's been plagiarized by many comics since then.