When a skeleton eats food, piles of food will spawn and if a skeleton drinks something, puddles spawn. They have special interactions like telling a skeleton joke or scaring a Sim.
It is possible to make a skeleton playable by using the cloning machine on one. Another way to make a skeleton playable is by enabling the testing cheats, shift-clicking on it, and then selecting the option to add it to the household. Either way, the added skeleton will have all skeleton features, except it will not be able to do special interactions like scaring or telling skeleton jokes. It will also have normal motives like other Sims. Trying to edit a skeleton will show it as a normal Sim, but no changes applied will be visible after exiting editing screen (except for a family screen picture, which also shows an added skeleton as a normal Sim). Skeletons added to the household in this manner are fully playable but may be removed from a family through a bug - using a relic to summon a skeleton helper can sometimes summon a playable skeleton, making it unplayable again and removing it from its family.
Added skeletons will have another glitch and will change their default colour (white, dark or blue, mosaic-like pattern) to another one from time to time. This becomes very evident when wearing earbuds.
Skeletons are also able to catch fire, but will never die from such.