Someone who lies about themselves in order to a) impress people (namely vulnerable/gullible men and women) and b) to evade the reality of who they are.
Most lies are erratic, far fetched and extreme exaggerations of true events.
Don: Yeah, I was out to dinner at the Ivy when she proposed to me but I said no....I own 3 properties in the UK....I have a PHd in Chemistry and went to Oxford University....But I had a job on the railways as a signalman, a train driver, all at Euston...I have so many fifty notes in pocket I need to get some change...Women only go for me because of the money I have...
Jim: Really mate? Then why are you driving a crappy van, living in a crappy apartment, borrowing money from your 'mates' and chasing after women half your age? You're such a Bullshitter.