Knee-slapper or rib-tickler (4)
I believe the answer is:
joke
(Other definitions for joke that I've seen before include "someone inadequate" , "Gag" , "Humorous remark" , "bit of humour" , "Crack in a cracker" .)
I believe the answer is:
joke
(Other definitions for joke that I've seen before include "someone inadequate" , "Gag" , "Humorous remark" , "bit of humour" , "Crack in a cracker" .)