/nÄ/ /slapper/
Noun
1. A joke; typically a pun or otherwise regarded âDad-Jokeâ, the humour of which prompts an audible slap-of-the-knee from one or more of the parties involved.
Ron: âSo me and the wife were down in Mexico last month, and she twisted her ankle at Salsa Nightâ.
Gord: âOh no, what did you do?â
Ron: âI called âNine-Juan-Juanââ.
*Audible laughter and slapping-of-the-knee*
Gord: âJesus Murphy, Ron, you really had me going there for a second. Now thatâs a Knee-Slapperâ.