I had an amusing encounter a few years ago. I was on my way to my local session and was asked by a lady of the evening "Do you want business luv?"

I looked at her, then looked up at my left shoulder, over which I was carrying a double bass. "Does it f~~ing look like it?" I said. She laughed.

Of course, in retrospect I wish I'd said something more witty, like "Why? Don't tell me you play the banjo".