With the BAWSAQ it's even easier than traditional pump-and-dump. If you pour a large enough pile of dough into a stock, it goes up a ton after a delay (1-2h). So, you can purchase all you want before the price skyrockets. Other players predictably pile on because they see the stock going up; which makes the stock go higher and entices even more players to invest in the stock.
You then sell all your stock for a tidy profit and watch the price, and the hopes of the other investors, collapse.
You then sell all your stock for a tidy profit and watch the price, and the hopes of the other investors, collapse.