Prince Charles decides to take up jogging. Every morning he jogs past a prostitute, who works the same street corner each day.
"One hundred and fifty pounds!" she shouts to him from the curb.
"No! Five pounds!" he fires back just to shut her up.
This becomes a daily ritual.
One day, Camilla decides that she wants to accompany Charles on his run. As the jogging couple near the working woman's street corner, the prince realises she'll bark her £150 offer, and Camilla will wonder what he's been doing on his morning outings.
As they approach the corner, sure enough, there's the prostitute. Charles tries to avoid eye contact as she watches the pair jogged past.
Then just as they pass, the prostitute mutters, "See what you get for five pounds, you tight bastard!"