knee-slapper

[ nee-slap-er ]
See synonyms for knee-slapper on Thesaurus.com
nounInformal.
  1. a joke evoking boisterous hilarity.

Origin of knee-slapper

1
An Americanism dating back to 1965–70

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024