Laughing Gas

Chakra is kneaded within the body and then changed into special chemical substances which is ejected through ones mouth. When this substance comes in contact with the air outside the body, it instantly changes and is transformed into a mist of deadly laughing gas. Those who inhale it enter an uncontrollable spasm of laughter. This jutsu can distract enemies long enough for the user to kill them, recruit them in being an ally, or just escape while The enemy is just lying on the ground helpless with uncontrollable laughter. If they laugh too hard, they could expel the air from their body which will lead to their death. Koshiro, the original user of this technique created a genetically altered version of, even just breathing in small amounts will mean the end of a victims life unless proper care is received. It is also possible that Koshiro's version also contains tetnus toxoid which causes lock jaw. Victims often exhibit a grotesque grinning expression called "Risus Sardonicus" due to spasms of the facial muscles. As this technique combines ninjutsu, chemistry, and medical knowledge, using it requires fine chakra control and advanced ability in medical ninjutsu.

Ninja Art: Laughing Gas serves as a perfect torture tool as users can force a victim to speak from their pain. What makes Laughing Gas such a dangerous technique is it's colorless trait. Making it hard to detect without some sort of chakra sensing or smelling it.

Trivia

 * Taken from Joker Venom