Unique ability: Smile goes a mile on the high road. All luxury resources grants +1 extra happiness, while the National Wonder Colosseum can be built without having a happiness building in every city. While the empire is in a happy state, their troops gets an extra 5% combat bonus for every 10 happiness points, and 5 gold for every 10 happiness points.
Unique building : Court Jester guild. Replaces spy guild. Can only be built once in the capital, but grants an empire wide -30% penalty to tech steal speed to their enemies. Also grants +4 happiness in the capital.
Unique unit: Warmaker. Replaces riflemen. Whenever the warmaker destroys a unit, that unit receives a 5 turn combat bonus of 10%, and grants +2 happiness to the closest friendly city owned by Jokesters.
Focus on traditionalism first for a strong capital with high happiness level. Try to obtain all possible luxury resources. Don't have too many cities or citizens that you don't need. Don't raze cities all the time. Build buildings with high happiness.
Pair with rationalism (+10% to science while empire is happy)