In professional wrestling, something that is "kayfabe" is not real, something that is "acted out" and not happening in real life. Many things in wrestling are kayfabe, that is, they appear to be real (such as the storylines), but are, in actuality, fake.
People who believe that kayfabe acts are real are called marks, as opposed to smarks. Those who know wrestling is scripted but still enjoy the storylines are known as smart-marks, or smarks.
It is unknown where the term came from; it is sometimes believed that the term "kayfabe" is a modification of the Pig latin word for "fake", "akefay".