high jinks

Short definition from Wiktionary

Noun

1. 1
   An old Scottish parlour game in which people were chosen, usually by throwing dice, to perform some humorous act or drink a large amount of an alcoholic beverage, with a forfeit if they were unable to do so.
2. 2
   Boisterous activity or behaviour; lively fun.
3. 3
   Tricky or waggish behaviour; mischief.