Nobody is quite sure where the term “kayfabe” originated. It may be a bastardized form of pig Latin, something to do with the actual word “fake.” It may have its roots in the culture of wandering 19th-century carnivals, the world inhabited by P.T. Barnum and the confidence men and the salesmen who sold actual snake oil.
Its modern usage, though, is sufficiently specific that only a relatively small proportion of people would even have a sense of what it means. Kayfabe is, essentially, the illusory cloak that is doggedly draped over professional wrestling: the maintenance of the pretense that what you see in the ring is unscripted, competitive, what we would consider real.