A fast food hack that's specifically about the burger place Five Guys has been going around on TikTok. But you could probably pull this off at other burger places too for not a lot of money. A TikTok account called HealthyJunkFood did a video on how you can turn one burger at Five Guys into two burgers for FREE.
A regular burger there comes with two patties. So just ask for all the toppings on the side, and order an extra bun. Extra buns are free, so it won't cost you anything. Then just move one of the patties to the extra bun, add the toppings yourself, and you end up with two burgers for the price of one.
Obviously you end up with two single cheeseburgers instead of a double. But their burgers are too big for a lot of people anyway. So even just one patty makes for a pretty big meal. They do sell something called a "Little Cheeseburger" that only comes with one patty. But they're not that much cheaper. So the hack does save you a few bucks. You can check out the TikTok video below.