In one of the Discworld books, there is a conversation in which Rincewind tries to justify his qualification as a wizard. He starts to say something like "I've passed dozens of exams" but catches the error and instead says something like "I've sat dozens of exams."
Can anyone help me to locate this quote? I think the last Discworld book I read was Men at Arms, and I have it in mind that the other individual in the conversation might have been Death (or Scrofula), but I'm not certain about that.