Indecent Proposal

"I'll give you a fiver."
The woman turned around and looked at the scruffily-dressed man lurking in the shop doorway.
"Excuse me?"
"I said I'll give you a fiver."
"What for?"
"You know."
"I think I know and I'm absolutely disgusted by the thought of it."
"Why?"
"I'm not going to sleep with you for a fiver. I'm not a cheap prostitute."
"How much then?"
"Ten."