A man and a hooker are starting a sexual encounter. He asks her to "go downtown" but offers her no money, so, with a sigh, she gets on her knees in front of him and starts peering at his genitals, looking and tipping her head this way and that, studying his business.

After a couple minutes of this, he asked her in a sort of peeved voice, "Er... what the hell are you doing?"

She says, "I'm doing what I always do when I'm downtown with no money.... just looking."