Essence of Imp Spray

This putrid substance is some unknowable combination of urine, bile, and pheromones exuded from the stink glands of the common imp. While communication via spray is well-documented in the natural world, imps are the only known creatures to employ spoken and sprayed language at once, doubling up on the two in singularly unpleasant exchanges. How much they get across to each other in their effluvium is anyone's guess, though anger and annoyance seem the pillars of imp conversation.