Something so toxic that when you inhale it you will die. The worst part is that his farts are silent but deadly that means you wont know he farted until it is too late. If Kairu says he farted just accept your fate and die to the fart.
Example of Kairu's Farts:
Guys run Kairu farted its gonna go nuclear.
Also
Guys if Kairu farts run for you lives.