The University of Wolverhampton in central England has found the world's oldest joke. It's a gag about breaking wind and dates from 4,000 years ago. The joke dates from 1900 BC, and originated in what is now southern Iraq. The joke goes:- "Something which has never occurred since time immemorial; a young woman farting in her husband's lap."
(Well I can only think that times and senses of humour must have changed since then.)