The MTA has unveiled a new ad campaign to remind subway and bus riders that those priority seats reserved for the disabled … are reserved for the disabled. In fact, it’s not just a matter of basic human decency it’s the law. And you can be fined $50 or sent to jail for a day for refusing to give up your seat for a disabled person who asks for it. Which is all well and good people should be doing that without the threat of incarceration anyway. But the definition of “disabled” is also deceptively vague. A line at the bottom of one subway poster reminds riders that “not all disabilities are visible.” In fact, they can include things like emphysema, congestive heart failure, and mental disabilities. So, who will be the first wretch to pretend to have an invisible disability for the benefit of a seat and who will be the first ballsy rider to call their bluff?