> You could even write it on the back of your Metrocard if you can figure out how to get ink to stay on it. If I want to write something on a credit card, I pu

> You could even write it on the back of your Metrocard if you can figure out how to get ink to stay on it. If I want to write something on a credit card, I put some clear tape over the ink afterward. I've never seen a MetroCard, but based on photos online, it looks like heavy paper stock with a glossy finish. So a sharpie and some clear tape should do the trick for the lifetime of the card.