Definition of knee-slapping in US English:

knee-slapping

adjective

North American
informal
  • See knee-slapper

    • ‘At this point, the entire kitchen erupted in knee-slapping laughter.’
    • ‘The show is a breath of fresh air, a knee-slapping good time, and chock full of real (non-CGI) stunts, races, and vehicle chases.’
    • ‘The voice chuckled, as if she had just made a knee-slapping good joke.’
    • ‘And despite the fact that there are lots of chuckles in The Ladykillers, there is nothing new or hilarious enough to inspire a knee-slapping good time.’
    • ‘What follows is a rare thing: a masterful Shakespearean spin-off - smart, fast moving, and littered with knee-slapping references to the original.’