Boisterous fun; uninhibited jollification; pranks and capers: the dashing hi-jinks of the Katzenjammer Kids/ The out-of-towner cuts the hijinks here
[1861+; fr the name of a dice game played for drinks, found from 1690]
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with high-jinks
Playful or rowdy activity, often involving mischievous pranks. For example, All sorts of high jinks go on at summer camp after “lights out.” About 1700 this term denoted a gambling game accompanied by much drinking, but by the mid-1800s it acquired its present meaning.