[ in-johk ]
/ ˈɪnˌdʒoʊk /
a joke that can be understood or appreciated only by the members of a limited group of people.
Origin of in-joke
First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Word Origin and History for in-joke
Online Etymology Dictionary, © 2010 Douglas Harper