McDonald's founder, Ray Kroc, was a brilliant businessman -- when he kept out of the kitchen. After buying the business's rights from the McDonald brothers, he expanded into new geographic markets but soon discovered a problem with the sales in regions with large Catholic populations.
According to church canon, Catholics over the age of 14 are required to abstain from meat on Fridays. Kroc had high hopes for his non-meat option called "The Hula Burger" -- grilled pineapple with cheese on a bun. He positioned his burger to compete against the Filet-o-Fish sandwich, which was invented by a Catholic franchisee. The Filet-o-Fish won hands down while the Hula tanked.
Since then, American Catholics have relaxed their traditional Friday custom. It's still popular to abstain from meat on Fridays during Lent, however, and McDonald's typically discounts the Filet-o-Fish sandwich during that time to boost sales.
Although Kroc managed to stop his Hula Burger short and avoided reaching national embarrassment, the company wasn't so lucky with these next flops.