This is attainable in Goat City Bay, and it is recommended that you use the Angel Goat + Double Jump mutators. You have to get to the top of the skyscraper in order to unlock this. The easiest way is to head inside, and use the elevator. Once on the roof, go on stage and headbutt
deadmau5 in order to gain this
If you're interested in also getting this achievement:
Instead of going inside and using the elevator, use the planter of trees to scale the back side of the building and you'll end up on top of the bar. Once there, you'll notice a mattress, which you want to jump into and then ragdoll
, and build height by bouncing on it. After about 3-5 bounces, you'll have enough height to go up, forward, and then land on the roof!
*Posting for MAKA91, because he is only playing the Xbox One version.