Hyrdogen Sulfide, which makes farts stinky, is apparently liquid at room temperature (or maybe you have to chill it a bit). Anyway, I know my chemistry said it was liquid at a relatively normal temp, so you could go spray it on say someone’s pants and then when they sat down, their body heat would turn it to vapor and it would smell really awful. He said he and the other chem PhD’s used to do this as a prank… Ah, grad student humor…