Thanks, that's the one.
The version I heard had another verse which goes like this, as near as I can recall it:

I was riding on a bus, it was a cold and breezy day
So I sat down on a newspaper to keep the chill away
A fellow sees the paper on which I just barely sat
and he speaks right up and says to me
Say, are you reading that?

Foolish question, so these words to him I spoke
As a matter of fact I am, I said, but he took that for a joke
So I got up and turned the page, and sat back down again
Foolish questions, you know you hear 'em now and then.