A witch who is bored might do ANYTHING. People said things like 'we had to make our own amusements in those days' as if this signified some kind of moral worth, and perhaps it did, but the last thing you wanted a witch to do was get bored and start making her own amusements, because witches sometimes had famously erratic ideas about what was amusing.

The IQ of a mob is the IQ of its dumbest member divided by the number of mobsters.

Knowing how bad you could be is a great encouragement to being good.

Pets are always a great help in times of stress. And in times of starvation too, o'course.

As far as Death was aware, the sole reason for any human association with pigs and lambs was as a prelude to chops and sausages. Quite why they should dress up for children’s wallpaper as well was a mystery. Hello, little folk, this is what you’re going to eat… He felt that if only he could find the key to it, he’d know a lot more about human beings.

A number of religions in Ankh-Morpork still practiced human sacrifice, except that they didn't really need to practice any more because they had got so good at it.

We are monkeys. We like to chatter. Chattering doesn't cost us anything.