2 memory lane is a bad address

A son, a grown man now visits his father to pick up his own son from a weekend visit with the grandparents, in his polo shirt he goes inside to see his father reading the newspaper. Still always dressing as if he is about to go out in his short sleeve button down shirt. "Hey dad, where's Oscar?" His dad looks up and smiles "out back, swimming in the pool" the son looks upset "and you watching him how while he's drinking a belly full of water?" The dad gets serious "look behind you I moved the mirror so I could see him from my chair" all of a sudden a roar and a tremble shake the house the son goes pale and terror takes him "it cant be......"