When you first spawn onto the payday map, press rb to change from the goat into the dolphin. When you become the dolphin, break out of your cage and break into the goat’s cage. Give the goat a lick so he is attached to you and go towards the town where the buildings are. The tallest building is the one with the blue sign on the front, because you are the dolphin you can ride up the side of the wall and as long as you still have the goat licked he will come with you up the wall. When you get to the top jump on the whoopee cushion while you still have the goat attached to you and your achievement will pop, simple as that.