Power Pellets as they are named, Power up PAC-MAN and turn the ghosts blue for a limited time. They’ll need to watch out from you this time, the hunter will become the hunted.
Psssst! After 17 stages of being eaten by PAC-MAN in the Classic Mazes, Power Pellets won’t turn the ghosts blue anymore (so it's best just to avoid them when you reach this point).