Inside the assassin's balls, there are two chambers. One filled with your poop and the other filled with horse poop. If you cover the hole on the horse poop chamber, it blocks the air coming in, which stops the horse poop from coming out, so only your poop will be poured in your balls.
Covering the hole on the poop chamber will allow only the horse poop to be poured out in the enemy's balls. Covering both holes makes it so nothing comes out. And pouring with both open allows the two hoops to mix together inside the assassin's ball.
