This week, Dunkin’ Donuts got the Internet buzzing by dropping its Glazed Donut Breakfast Sandwich, a gluttonous creation featuring bacon and eggs stuffed between two glazed doughnuts. On paper, it’s not much of a stretch from the infamous Luther burger, or doughnut burger, that pops up from time-to-time at publicity-starved restaurants across the country. But within the fast-food world, it represents an ever-growing trend toward mash-up cuisine, or Franken-foods, in which two previously distinct items are combined into one loud package. Doritos and tacos. Dessert and pizza. Burgers and nachos.

These mash-up creations have become increasingly popular, and we’d surmise that there are two main reasons: 1) They are easy to understand, since they take two things that already exist and that people are familiar with and combine them into one over-the-top item—this is, by and large, how all creativity works in the Internet age. 2) They often allow chains to compete in new areas by creating ambiguous foods that are not recognizably breakfast, lunch, or dinner. Taco Bell wants a share of the breakfast market, so it recently dropped its waffle taco. When IHOP puts a cheesecake in between pancakes, it can get you salivating at 10am and 10pm.

If you look at the history of fast-food mash-ups, Pizza Hut and Taco Bell are the clear game-changers, pushing the boundaries of their offerings as often as they can. What’s also interesting is how popular this trend is at international outposts of franchises—Pizza Hut Middle East seems to make headlines every other day with its creations such as cream-cheese cone crust pizzas and Kit Kat-stuffed breadsticks. Perhaps there’s no better representative of all-American excess than the junk food mash-up.

Click through the gallery above for the key touchstones of fast-food mash-ups in recent history.