I was giving out copies of my wonderful C# notes (known in the department as the "Yellow Book" for reasons which become very obvious when you see a copy). In a rash moment I said that I paid a standard rate of a bottle of beer for every error that people found. This is kind of true, and usually a very cheap way of employing proof readers.
Of course, the next thing that happened was that someone found a typing mistake. But not just anyone, a charming young daughter of one of the visitors. Who was way to young for a bottle of Budweiser. I think we will send her a T shirt instead.
I'm now off to write "I must keep my stupid mouth shut" 100 times.