this is due to insecurity.
girl1: the dude who plays harry potter bought me this bracelet!!!
girl2 to girl3: she is such a liar!
1. someone who represents one set of facts, while knowing that a
different set of facts prevails;
2. (popular) someone who having led others to believe one thing, does
a different thing; a promise-breaker;
3. (colloquial) someone whose general conduct, level of reliability,
relationship with truth, and past preformance leave him or her with
little to no credibility in peoples' opinion;
Ministers Stephen Harper and Brian Mulroney, along with a pissant
Minister of Defence Peter MacKay.