Filling the Joke Master aspiration gives your sim some new joke socials. I had a dinner party going on and queued up several social interactions in a large group conversation (4+ sims) including a new joke type, the Weaponized Joke. I then moved on to queue up a few more socials on another sim when....
*Every* sim lost bladder control *except* the Comedian. Weaponized Joke turned a pleasant party into a house full of Mortified or Dazed people. I quickly cancelled the party and sent all my household sims down for a nap (sleep emotion overrides everything!) until the stack of embarrassed icons disappeared.
I made the Comedian (who was immune to her own joke) mop up the living room, which was nothing but a sea of puddles.
So take warning, that Joke is potentially *lethal*! I'm not sure I even want to touch the Horrifying Joke.