What does the phrase "Does the Pope sh** in the woods?" mean?

It is a mixture of two sayings meaning the same thing, mixed together for comedy value:

Is the Pope Catholic?

Do bears sh*t in the woods?

Obviously, the point is that the answer to both questions is obviously "yes".

UPDATED- As Tim correctly points out, the deliberate irony is that the actual answer to this question is presumably "no" (although he does have a wood nearby...).

It's a mash-up of two very popular phrases: "Is the pope Catholic?" (well, of course he is!) and "does a bear shit in the woods?" (where else would he do it?)

It's a humorous but very rude way to say "Of course - why would you even ask?"

Urban dictionary has a sensible explanation:

This is a sarcastic answer to a question with an obvious answer of "yes." Taken as a combination of the similarly-intended ones, "Does a bear shit in the woods?" and "Is the Pope Catholic?"