The term booby-dazzler is not one you will find in the dictionary, and I would highly advise against googling it--I don't want to be responsible for whatever happens there. The word has made its way into my vocabulary trickling down through the generations from my Grandmother, who to this day, frequently uses the word. Instead of defining it myself, I went straight to a more knowledgeable source: my mother. Here is her definition:
Booby-Dazzler: "So amazing, so extraordinarily conspicuous; the ultimate in whatever commodity. Usually a sandwich."
So, although the term begins as an adjective, it has become so descriptive that it can be used as a noun. So instead of saying "What a booby-dazzler sandwich!", you might instead reflect "This sandwich is a real booby-dazzler!"
I would like to take this opportunity to add that my Grandmother's homemade "Spudnuts" (aka. mouthwatering doughnuts), are also commonly referred to as booby-dazzlers. That is all.