This is attainable in Goat Ville.
At the construction site, on the next to top floor closest to the street (the floor just below the 10 yellow canisters in the same corner), there are a bunch of mattresses lying on the floor. You need to jump on these mattresses 100 times within 30 seconds. After the second or third jump, it can get kinda hectic as it speeds up considerably and you keep moving from side to side and may bounce off or even fall from the floor to a lower floor or the ground below. Use
to move the camera so it is facing the ground and use
to keep the goat on the mattresses. If you bounce off of them, simply jump back on. There is really no way to tell how many times you’ve bounced since it goes so fast, so just keep at it until the achievement unlocks.
Note: Turning on the Tall Goat mutator might make this easier since there is less room to bounce around. To unlock this mutator, you need to collect five golden trophies in Goat Ville.