1) Buy the Scooter Dash Badge from the Badge Seller. This will change your basic sprinting into riding a scooter, like in the Subcon act where you're to deliver letters for the Snatcher.
2) Return to the Boss Act in Mafia Town and ascend to the Mafia Casino. Instead of aiding Mustache Girl, equip your Sprint Hat and put on the Scooter Badge. Drive off the edge and start spinning. You should get the trophy before it unloads you and puts you back up on the casino platform.