If the lady had said "Can you spare a few minutes to discuss supporting cancer research" there isn't any ambiguity in the sentence and then no joke.
Community used these to great effect. For example:
Britta: Yep, I’m getting serious. I got a backpack, got a new notebook. Oh, I got one of those see-through yellow pens so I can do that thing where you colour in the words.
Shirley: Highlight?
Britta: Probably the backpack.