tip the gaff

English

Verb

tip the gaff (third-person singular simple present tips the gaff, present participle tipping the gaff, simple past and past participle tipped the gaff)

1. To give away how a magic trick is accomplished.
   • 1989, Calvin Trillin, “A Couple of Eccentric Guys”, in The New Yorker:

     Penn and Teller see their style as rejecting the assumption that “the people in the audience are ignorant savages who will fall at our feet and worship us for performing supernatural miracles.” Penn may enjoy describing the “Penn & Teller” approach to magic as tipping the gaff...

2. To reveal a disguise or something hidden.
   • 1914: The Smart Set: A Magazine of Cleverness, Volume 42, "The Parasite" by George Bronson-Howard

     Lady! She couldn't disguise herself as a lady with that Slavonic map of hers tipping the gaff, and those heavy hoofs of hers.