Compulsive lying.

[Buelligan]

The lie is, I always tell the truth.

Edit: Except when it comes to steam trains

Well, they certainly put a crease in your flannels far better than the modern electric rubbish.

[Cerys]

My compulsive lies (a) aren't compulsive, and (b) aren't intended to be believed.  Although it's kind of fun when they are.

[gilbertharding]

I absolutely love a compulsive bullshitter, they're my favourite people.

They're fine. Trouble comes, I think, when you are the only one who knows that they're bullshitting. If everyone else believes them, it can get nasty.

[petril]

I know someone like that, an adult.  I don't know them any more because I refuse to have any contact with them and have moved countries without leaving a forwarding address.  But I did know someone like that.  They did the most dreadfully terrible cruel things, beyond belief - terrible evil betrayals - you can't even begin to imagine.  I'm not sure if they entirely believed their own lies because when we were alone, they would smirk and hiss.  Nevertheless, I congratulate you on leaving this habit behind, in some cases it can grow into something truly monstrous.  I am not even lying.

and that thing will be in the inner pages of the newspaper, in a story with the words "fabricated", "medals", "character", "Walter" and "Mitty". no coming back from that

[gilbertharding]

I've mentioned him before, but I was at school with someone of whom I next heard when he was exposed as having fabricated an interview with Stanley Kubrick. He then served a prison sentence for stealing and selling archive photographs.

I could have predicted all of this happening 20 years earlier.