Raider of the Lost Parking Garage Achievement in Goat Simulator 3

In southeastern Downtime, there is a small car garage with a barely open door (screenshot below). To get in, I just ran at the door and then pressed  to ragdoll under it, through the opening. Once inside, there will be a perfectly round boulder. Simply lick it to unlock this achievement. As a side note, there is a trinket inside behind the boulder too.