The images most likely to burn in are anything with high contrast. A bright white "Bravo" logo in the lower right corner of your TV marathon might stick around long after the Top Chef is crowned.
But the good news is fixing a moderate burn-in is easy!
All you need to do is round up your iPhone, iPod or laptop and hook it up to display on your TV. Pull up your favorite photo slide show and set it to "full screen."
If you leave the TV on for a few hours with a constantly changing image that fills the screen (a screen saver would work, too!), any burned in image should fade quickly.
Oh and about that 100-hours rule? Experts say that burn-in is most likely to happen in the first 100 hours of watching a new TV. So if you're bringing home a new plasma, keep contrast low (less than 50 percent) and be extra mindful of letterbox bars and static images.