Unproduced TV story
The Jokers is an unproduced episode of Doctor Who. It was one of the original proposals that were eventually scrapped. (TEDW 12)
Ian and Barbara find themselves in an alternate version of 1943 where laughter is against the law. But they meet a group of rebels, keeping the flame of humour alive. (TEDW 12)
The later produced episode The Happiness Patrol featured a similiar plot, but, ironically, with the exact opposite concept, as in it was against the law to be unhappy in The Happiness Patrol.