Your pickups will develop myopia. Also it depends on what programme the TV is showing. If it's watching teletubbies it may develop hippie tendencies, if it's Alias it'll start drooling at the sight of Jessica Alba, if it's pokemon it may have epileptic seizures.
Seriously, if your guitar is not plugged in, nothing's gonna happen. Unless you leave the TV on and the guitar glued to it for 1 million years, then maybe the electromagnetic fields will demagnetize the pickups. If you have it plugged it you'll just get hiss :wink: