i have just recieved $50k on my credit card..., page-62

If you had been credited with $50,000 to your account you would also recieve interest monthly for being in the black.
You can run your credit card in the black instead of the red any time by putting extra money in. very few people do that, but its a good idea if you are travelling abroad and use atm's then you dont get charged interest right away and are using your own money. However it is a bank scam as they have only raised your credit limit in an attempt to get you more in debt.