How about really good products that failed miserably, because people can't math? Like A&W's 1/3 pound burger. People bought McD's over A&W because, "1/3 of a pound is less than 1/4 of a pound, because 4 is bigger than 3." Seriously.
BEHOLD….. The FIVE FIFTEENTHS BURGER!!!!!
Muahahahahajajahahaha! Suck it, Ronald, you failed clown.