And Hair Color So Natural, Only Your Undertaker Knows For Sure

I realized I've been doing all of these Batman related posts and never statted out the Joker's special gas. You'll find rules for Smilex below. I've also updated my Joker, Bob the Goon, Batman Who Laughs, Joker (Tommy Wiseau) and Gaggy stats to reflect this.

Smilex

Also known as Happy Gas, Joker Venom, and Joker Toxin is an insidious nerve agent. It causes those that inhale it to laugh uncontrollably as their faces are stretched into a Joker-like grin. The most common version of the gas effects individuals as a Hideous Laughter spell (DC 15). However the 

concentrated version is far more dangerous. Anyone inhaling it must make a make a Wis saving throw (DC 15) or perceive everything as hilariously funny and gain a level of exhaustion. For every minute of laughter they gain a level of exhaust.  A creature with intelligence score of 4 or less isn't affected. At the end of each of its turns, and each time it takes damage, the target can make another Wisdom saving throw. The target has advantage on the saving throw if it's triggered by damage. On a success, the effect ends. 

Joker Antitoxin

As a bonus action, this antitoxin can be administered to someone suffering from the effects of Smilex. The effects end (though any levels of exhaustion gained remain).