You’re mad, bonkers, off your head … but I’ll tell you a secret … all of the best people are.

Lewis Carroll (1832-1898) English writer and mathematician [pseud. of Rev. Charles Lutwidge Dodgson]

(Spurious)

This is attributed on many pages as a quote from Carroll's Alice in Wonderland. No such quote exists in the book, and the word "bonkers" does not appear until the 1940s. This appears to be a paraphrase of lines from the 2010 Tim Burton adaptation of Carroll's work (screenplay by Linda Woolverton):

HATTER: Have I gone mad?
ALICE: [checking his temperature] I'm afraid so. You're entirely bonkers. But I'll tell you a secret. All the best people are.