"Someone's been keeping something on me," Rincewind mutters darkly. "That never happened when I was on Fourecks," he explains. "I'd lift up a rock and there was dinner."
Rincewind peers at the page. "I don't see anything special about his knee," he says. "You can't even see them; those boards are in the way."*
"I know," Rincewind sighs, long-suffering. "They get bored. They do this sort of thing for fun."
*Sorry. Well no, I'm not. Sometimes you just have to take the ball and run with it! :D