they just like sending PM asking you "do you wanna rob the bank with me? i got a perfect plan and will never get cought by police."
In Czech republic exist one forum where is topic with that kind of activities. You can earn fictive money and these can use to pay activities of this kind. People write topics like I will pay xx fictive money for click on my ad, send your userid if you do click and I will pay you. for example. It looks like good business , because a lot of people is joined there. But I am sure that it is only question of time, when they will be banned.