After banning hoverboards from New York City's subways, trains, and busses last month, the Metropolitan Transportation Authority has begun rolling out new ads, first spotted by Gothamist, to make sure you get the message. The new ads make it clear that passengers cannot transport or ride hoverboards in any manner on MTA-controlled transit, stating "hoverboards may be the latest fad, but they are not safe because they have the potential to catch fire."