“Insanity is catching.”

“...rational thoughts made out of insane components.”

“Five exclamation marks, the sure sign of an insane mind.”

“Do you think it's possible for an entire nation to be insane?”

“What did I tell you about Mister Safety Catch?' said Vimes weakly. When Mister Safety Catch Is Not On, Mister Crossbow Is Not Your Friend,' recited Detritus, saluting.”

“When Mister Safety Catch Is Not On, Mister Crossbow Is Not Your Friend.”

“I think it's IMPOSSIBLE for anyone famous to come from here, because everyone around here is insane.”