How to be cool when you're afraid you've forgotten how . . . Sure, you can try to stay younger by exercising, coloring your hair, and wearing stylish clothes--but how do you respond when someone asks, Do you Twitter? How Not to Act Old gives you simple ways to come back from over the hill and to act as young as you look. Covering everything from old-people entertainment (cancel that dinner party ) to old-people communication (it's...