How do you double money on RuneScape?

You cant, it is a scam people do they tell you that and then steal your money or you do it to them, you can get banned for this and it is incredibly annoying, it became popular after free trade update. Similar scams are dice game, flower game. for future reference people normally do it together, for example someone is the "doubler" and his friend tells everyone he is legit and telling them the "doubler" just doubled his money. If you trade them they will often do a few low doubles and then get a someone to do a big one and the "team" logs .........do not fall for it, a good thing to learn in runescape and life, nothing is free