The items listed in the site's directory include both the officially unofficial creations of the restaurant's themselves and also DIY inventions you can either make yourself, by combining several conventional orders, or convince a particularly game cashier to whip up.
A spokeswoman for Burger King denied having a secret menu and said 'Our restaurants are committed to providing our guests with choice, and all customers are able to customize their order, by adding ingredients to our menu offerings.'
Subway claimed the same. A spokeswoman for the brand said: 'All Subway stores are independently owned and operated by franchisees. Whilst we only have one core menu, the Subway brand prides itself on offering choice to customers so that they can have their Sub made the way they like it.'
The Suicide Burger - Hack the Menu lists eight under-the-radar treats for Burger King but, at a fast food joint famed for its liberal use of cheese and bacon, the Suicide Burger is the stand out, with its four beef burgers, four slices of cheese and four rashers of bacon crammed between two buns.
The site claims the burger is available at all outlets - although sometimes under the name The Quadstack - for $3.99. However, in the event that a cashier stares blankly after receiving the order, customers are advised to simply describe it ingredient by ingredient.
The Monster Mac - Perhaps more aptly called the Bigger Mac, this gut stretching creation is simply a normal Big Mac - but with six extra beef patties shoved in.
According to the Hack the Menu team, the burger is 'enough to satisfy a few people with hearty appetites or one hungry lumberjack' and can be ordered from any McDonalds for $6.49.
Liquid Cocaine - Not quite as illicit as the Class A drug but this drink is still a wink-wink, nudge-nudge purchase. This customer-invented beverage is supposedly 'one of the most intense drinks you can get, it's guaranteed to shock your system'.
Made up of four shots of espresso, four pumps of white chocolate syrup, ice and milk, the site suggests showing this recipe to your local barista as a how-to-guide.
Its DIY nature means there is no fixed price but the website said it should be standard for whatever size you order.
Triple Down - Strictly for an American audience, the Triple Down is a riff on the infamous Double Down, which was released in US outlets in 2010.
It is a double-decker egg, bacon and cheese sandwich, but, instead of bread, the filling is sandwiched between fried chicken.
Hack the Menu warns: 'Not too many people are willing to try something this big, but don't be afraid to ask them for this behemoth if you're really hungry'.
While the Double Down is no longer available, the Hack the Menu team assure readers that if they ask nicely, its larger cousin can still be whipped up (for a variable cost).
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