For a long time, I thought the only difference between Miracle Whip and mayonnaise is that Miracle Whip has sugar in it. But that's far from the whole story. I was never a fan of mayonnaise, but I learned in chemistry class that it's an emulsion of eggs and oil with a little lemon juice or vinegar added for tang. That was a fun day in class. Meanwhile, Miracle Whip is a brand name for "salad dressing." I've never known anyone to use it on a regular salad, but it comes in handy for potato salad or tuna salad, if you don't just use mayonnaise.
Miracle Whip was unveiled in 1933 as a cheaper alternative to mayo. When oil was expensive, people came up with a recipe for "boiled dressing" that used a lot more ingredients but got the job done. Kraft combined this alternative recipe with mayonnaise to make a lighter, sweeter dressing they called Miracle Whip. Read about boiled dressing and how it led to Miracle Whip at Mental Floss.
It is welcomed basically nowhere in anything I consume. And hats off to Matthew Inman. Didn't think he had it in him given his freakish obsession with Sriracha.