Any person who is given to large bouts of hyperbole and/or exaggeration. Claims regarding facets of his or her life will sometimes seem plausible until combined with the multitude of other experiences and/or possessions he or she claims to have had.
Jill: "Apparently he claims to be a good friend of Matt Shadows of Avenged Sevenfold."
Jack: "Even though he's 13 years Shadows' senior and has absolutely nothing in common with him?"
Jack: "What a total bragavond."