Since there aren't 5 people always online who want to lose rating on an account, the best way to lose rating with 2-3 people is by feeding the enemy hero kills.
Now of course if you say, feed or throw in chat, that's a red flag and it'll get you banned if someone reports you. So we needed to make up a short one syllable word to describe losing a game on purpose via playing poorly/feeding. And roop was born. Credit to Undeadgad for this word, in Swedish it means gay anal sex without lube.
So when someone wants to roop or go rooping, it means they want to lower rating on an account by feeding.
With the advent of rooping, there has been a side effect we have found that adds another layer of satisfaction, people getting mad. Getting your teammates mad is fucking hilarious. If you play with 2-3 people it'll ensure the loss, and it'll give you a chance to play with people who take the game way too seriously. Missing spells and getting your teammates killed is fucking hilarious. Feeding the enemy is actually fun. Some times we hold contests to see who can die the most.
One of our Jspers (rowe), died 32 times in 15 minutes. It was quite a feat to hold. As he randomed a hero with a blink spell (for faster dying), and with that starting gold he was able to buy striders (to run faster to his death). On top of that the enemy player gladiator bought doombringers so we'd die really fast. If you try to do this now, you'll likely get banned. This contest was held when the RAP was down, and you could only report people by e-mail.
We've also tried to roop in league of legends, some how with me dying 31 times and my fellow jsper feeding and then leaving, my team still won.
Roop also has another definition. Sometimes we use it in a serious game after you had a really bad teammate(s). If your teammate engineer missed all his spells and kept getting picked off, after the game you'd post on the forum and say you got rooped by an engineer. The engineer probably wasn't trying to lose the game on purpose, he was just really bad, or from Brazil/Russia. So roop can also be used as an insult when us Jspers play together in a serious game. So if i'm playing with iffy1, and he rices all game, gets bad items and skill choices, I blame the loss on him and say he rooped me. Even though iffy1 wasn't trying to lose on purpose, he's just really bad.