1) Details, used as shorthand, often on the internet, and often used in the command form.
2) A "clan" of kids who used to terrorize Seattle. They called themselves Clan Deets because they would always go "Deets", or "Downtown" on Friday afternoons.
"Deets", Verb. The act of obtaining something illegally using someone elses details. If you "Deets" something it means you got it illegally through using someones details.