OLD USE: Used to play a competitive racquet game.
NEW USE: This furry, yellow orb has many other uses. Hang one from your garage ceiling to indicate the perfect distance from walls or other objects when you're parking. Toss one in the dryer to fluff up pillows or blankets. Is there an oily sheen on the surface of your swimming pool from tanning lotion? Let a couple of tennis balls float in the water; they will absorb the oil, leaving your pool fresh and clean.