Things You Can't Buy With a Credit Card (Like Pot) MarketWatch rounds up 10 examples where plastic is forbidden By Matt Cantor, Newser User Posted Jan 25, 2014 4:20 PM CST 18 comments Comments Cash only, please. (AP Photo/Matilde Campodonico) (Newser) – Don't give up on cash just yet: There are plenty of items that remain difficult or impossible to get with your credit card, MarketWatch reports. Ten reasons you may want to keep going to the ATM: Neither Visa, MasterCard, nor American Express will let you buy marijuana with plastic, despite its legalization in some states. "We’re facing a situation where there’s an inconsistency between federal and state laws," says a MasterCard rep. Fans of WikiLeaks will need MasterCard if they want to donate to the site by card. Both Visa and MasterCard banned donations in 2010, but MasterCard now works. AmEx won't let you donate, the company says, even if the site claims otherwise. You can't use AmEx for any porn; the company says it's because of concerns about child pornography. MasterCard and Visa will let you use your card for anything legal, they say, though what's legal can be unclear when it comes to such websites. Gambling typically requires cash for chips, but there's an easy workaround, MarketWatch notes: You can get a cash advance by using your card at a casino ATM. In your own state, you can use MasterCard to gamble—if it's legal. Some colleges won't let you pay your tuition by card. Those that do may require a fee. And you can't pay federal student loans using your card unless you've defaulted. For the full list, head to MarketWatch.