I have a "friend" that is a compulsive liar - to the extent that I truly believe he is in some way sick. He is a drama queen fantasist, cue lots of text messages along the lines of "Suicide is the only option if you don't help me" and I've had to draw a line under it all and steer well clear. He's borrowed money and never repaid it etc. His latest fantasy was that he'd rejoined the Army, on his Facebook page there is all this stuff from random "friends" asking where he's been posted to etc when in truth he's on the dole....tried telling me he rejoined on a short commission (c. 6 weeks) - now I'm not connected to the forces in any way, but that didn't really ring true to me.
Having said all this, to my shame I actually didn't believe him when he told me his Dad had died (because he'd wrapped this all up in a need to borrow some cash for funeral arrangements and I honestly thought he would stoop that low).
Trouble is that he's a likeable guy and good company but quite why he lies about literally everything is a mystery - all very sad.