A person who makes his living collecting discarded betting tickets at horse racing tracks, then going through them looking for winning slips that were accidentally thrown away.
Among Irish Republicans in Northern Ireland, a "stooper" is an insult for a Catholic who isn't sufficiently nationalist; who is suspected of harbouring pro-British sympathies; who "stoops" (bows and scrapes, kowtows) to the Queen of England, and submits to the hegemony of the Unionist ascendancy.
Usually it just means somebody who supports the SDLP instead of Sinn Féin, but since the Good Friday Agreement the ultra diehards have started to regard Shinners as just another set of stoopers.
The state of mind after a night of drinking, being severely hungover, not understanding the world, asking yourself the question "what is life?". Can also happen after doing drugs. Can lead to severe facebook stalking/commenting, and writing embarrassing things on the internet. Stooper is much like being in a cloud. It is a state of mind.
The term "stooper" is associated with the adjective "ganked" (see example). A "stooper" is significant, because when a post is located at the top of a page, it will be seen (by most users) every time the page is loaded.
:: in a forum conversation, as if this were top of page ::
Swood: I disagree, the Shins pretty much such my nuts. I hope they never come back to concert in Minneapolis.
Woogums: Ohhh Swood.. you just ganked the stooper..