buttered side down.

Do I reference this more than the Penn Gillette chocolate & bacon theory? In any case, it's much harder to find.

“One day a teacher named Murphy wanted to demonstrate the laws of probability to his mathematics class. He had 30 of his students spread peanut butter on slices of bread, and then toss the bread in the air to see if half would fall on the dry side and half on the buttered side. As it turns out, 29 of the slices landed peanut butter side on the floor, while the thirtieth stuck to the ceiling.”

Turns out it's merely one of many unproven theories as to who was the Murphy in Murphy's Law, from Morris Dictionary of Word and Phrase Origins.
(Cited here.)

buttered side down.

Do I reference this more than the Penn Gillette chocolate & bacon theory? In any case, it's much harder to find.

“One day a teacher named Murphy wanted to demonstrate the laws of probability to his mathematics class. He had 30 of his students spread peanut butter on slices of bread, and then toss the bread in the air to see if half would fall on the dry side and half on the buttered side. As it turns out, 29 of the slices landed peanut butter side on the floor, while the thirtieth stuck to the ceiling.”

Turns out it's merely one of many unproven theories as to who was the Murphy in Murphy's Law, from Morris Dictionary of Word and Phrase Origins.
(Cited here.)