What could be the world's oldest joke has been found on a tablet dating back to 1900BC in Sumeria, now southern Iraq.

The "hilarious" gag reads: "Something which has never occurred since time immemorial: a young woman did not fart in her husband's lap."

The tablet shows that toilet humour dates back as far as man can dream.

Why not suggest readers send in their examples of old gags and see what local historians can offer in the way of centuries-old humour.