Imagine the worst smell you can think of. Now imagine the scent of “butt crack…with a hint of dead animal.” That’s how Allen Wittman, 45, describes his creation, Liquid ASS—a smelly spray initially intended to be used in pranks. “We package Liquid ASS in a bottle small enough to hide in the palm of your hand. The bottle dispenses our nasty elixir in a thin, invisible, silent stream, thus equipping the prankster with stealth and speed,” reads a product description, per the 99% Invisible podcast. Available for $10 on Amazon, it’s now used by the US military to harden medics to the smell of a torn intestine leaking waste. Yes, it’s that bad. Metro describes the scent as “the most appalling smell known to humanity,” adding the product lets you “recreate the smell of festival toilets, a soiled [diaper], or a burst sewer in the comfort of your own home.”