A catastrophic event or injury caused by improper use of a wiimote. Putting the wiimote through a window or TV, striking a friend or pet, any one of these can be a wiitastrophe.
Kyle didn't put the wrist strap on to play tennis. He went for an overhead smash to win the match and lost control of the wiimote which hit his plasma TV. The TV then fell into his fish tank, breaking it and sending a tsunami across his basement which drowned his cat. It was a wiitastrophe.