It actually originated as a patronising "you are too ridiculous to respond too, have a biscuit"
Used on threads, for example, where the OP was being a complete dick about a first world problem and acting like a princess. Or when someone is being so much of a dick and fails to see it, despite the whole thread telling them so.
Eg:
OP: "My selfish sister won't watch my DC for free any more and she's only done it for 2 years anyway. I can't sleep and I'll have to quit my job because of it. So I'm suing her for my loss of earnings too, because now I can't afford my personal trainer."
Poster: 