When someone across the internet makes unbelievable claims without any proof of backing it up and does it repeatedly. They usually do it because they have low self-esteem and want people to like them. Since nobody really knows if someone over the internet is lying or telling the truth.
Person1: Yeah, so I've had sex with over 100 girls, I'm a millionaire, I've got way over 500 cars, and I live in a mansion.
Person2: Oh cool, can I see some pictures of your mansion and cars?
Person1: Oh, sorry, I don't have a camera =(.
Person2: So let me get this straight, you're a millionaire and you live in a mansion, but you can't even buy a measly camera? Dude, you have ILS.
Person1: What's ILS?
Person2: Internet Lying Syndrome.