In the omake "Luffy's Day Out," the author (rose7anne101, Black Victor's beta reader) references ten food challenges from real-life restaurants:
The "Circle of Doom" is the "Drunken Fireman" from Giuseppe's Pizzeria in Covington, KY (now defunct).
The "Big T Toast" is the "Louisville Lip" from 502 Café in Louisville, KY (now a food truck).
The "Hop on Whopping Burger" is the "Quadruple Bypass Burger" from Heart Attack Grill in Las Vegas, NV. And that's half of the maximum size.
The "BS Combo" is the "One Tall Order" from Windy City Beefs-N-Dogs in Las Vegas, NV. Real-life version is 7.2 pounds instead of 9.
The "Almighty Burger" is the "8th Wonder" from the Clinton Station Diner in Clinton, NJ. The real version does not have thirty sides as part of the challenge; the burger is designed for nine people on its own.
The "Combo of Big Fat" is the "Big Fat Ugly Sandwich" from Fat Sandwich Company in Champaign, IL.
The "Steak Meteor" is the 72 oz. steak challenge from The Big Texan Steak Ranch & Brewery in Amarillo, TX.
The "Pound the Pounder" is the "Carnivore Challenge" from Big Pie in the Sky Pizzeria in Kennesaw, GA. The real version has five meats as toppings.
The chosen name is likely a reference to another pizzeria, Pizza By the Pound in Paducah, KY, and its own eating challenge: the Pounder, an 8-pound, 16-inch pizza with an extra thick crust and eight toppings.
The "Prisoner's Pardon" (actual name) is from Jailhouse Pizza in Brandenburg, KY.
The "United Meat" is "The Bomb" from Paddy Long's Beer & Bacon Pub in Chicago, IL.
When the Straw Hats raid a secret base in the desert responsible for developing five children into the Royal Flush Gang, they travel there in an oversized blue and red semi-truck. When they arrive, said semi transforms into a giant robot. That's right: Franky took inspiration from the Transformers series and built Super Optimus Prime. this giant robot is programmed to spout out plenty of cool one liners (lifted straight from the movies) while its performing its assigned task, and works on voice recognition, so it only seems like it's sentient at first glance. Nevertheless, Word of God says that the robot becoming sentient isn't in the plans.
The prototype Royal Flush Gang in Chapter 18 consist of four different expies:
