A.E Pessimal's attack on the troll. With his teeth. 'Mr. A.E Pessimal? You are sure? Small man? Very clean shoes?'

Any mention of Bloody Stupid Johnson.

From Thud, Colon and Nobby's musings on the difference between Art and pornography.

Captain Carrot's Repeat After Me scene in Men At Arms.

"I comma square bracket recruit's name square bracket comma do solemnly swear by square bracket recruit's deity of choice square bracket to uphold the Laws and Ordinances of the city of Ankh-Morpork comma serve the public trust comma and defend the subjects of His stroke Her bracket delete whichever is inappropriate bracket Majesty bracket name of reigning monarch bracket without fear comma favour comma or thought of personal safety semi-colon to pursue evildoers and protect the innocent comma laying down my life if necessary in the cause of said duty comma so help me bracket aforesaid deity bracket full stop Gods Save the King stroke Queen bracket delete whichever is inappropriate bracket full stop."

When Agnes Nitt in Maskerade is shown how to sing an opera song by the musical director, and is told 'just like that' she sings in Tenor. The man tells her to sing like Christine (her rival in the book) she sings in a high, breathy tone (Kewsta!? Mallydetta?! Porter see bloker?!) and is told then to "Sing it the way it was meant to be sung" ... and is shooed out off the office while he wipes his glasses with his back turned. (He's crying.)

Nobby's Bavarian Fire Drill in Men At Arms.

From "The Last Continent":

"One opened up in the cellars, once. Just a round black hole. Anything you put in it just disappeared. So old Archchancellor Weatherwax had a privy built over it." "Very sensible idea."
"We thought so too, until we found the other one that had opened in the attic. Turned out to be the other side of the same hole. I'm sure I don't need to draw you a picture."
"I've never heard of these. The possibilities are amazing!"
"Everyone says that when they first hear about them. But when you've been a wizard as long as I have, my boy, you'll learn that as soon as you find something that offers amazing possibilities for the improvement of the human condition it's best to put the lid back on and pretend it never happened."
"But if you could get one to open above the other you could drop something through the bottom hole and it'd come out of the top hole and fall through the bottom hole again... It'd reach meteoric speed and the amount of power you could generate would be-"
"That's pretty much what happened between the attic and the cellar. Thank goodness for air friction, that's all I'll say."

Pyramids: The camel is actually a mathmatical genius.

Soul Music.

In general.