Why does bread always fall buttered side down?

Mine doesn't. You must have done something to piss off the butter gods.

In actuality, bread doesn't ALWAYS fall buttered side down, but it does far more often than not for a very simple reason: as a general rule, the side with butter, jam, or other spread applied is almost always heavier than the other. This moves the "center of gravity" (if that term can be applied to a slice of something) toward that side so that when the bread falls free it tends to go spread side down. No mystique involved!

Quantum physics.

It doesn't. The MythBusters actually tested this and found that it fell butter-side-up more times than butter-side-down.

because life is cruel.

well, i have to say, mine does also. Gravity I suppose? or the butter gods, that works too.

The buttered side weighs more and usually buttered bread gets butter slapped on its face.

Butter fingers most likely.

Because you only remember the times it falls butter side down.

well, i have to say, mine does also. Gravity I suppose? or the butter gods, that works too.

Because the bread wants you to clean up the mess it made!

When bread with butter falls, it mostly falls with the butter side down only to signify one's badluck...

I have never taken note of which side my bread lands on. I mean, even if it landed butter side up, I'm not going to pick it up off the floor and eat it.

As an experiment i threw toasts 100 times high into the air in a random manner. The outcome was that in 63 cases the buttered side went down. The chance to get that outcome if it actually didn't matter which side was buttered is less than 2% and thus it's fairly justified to say that toasts more often end up with the buttered side down!

In addition to the centre of gravity explanation, bread tends to fall buttered side down because it was held buttered side up prior to the fall, Since usually, the fall height is about the height if a typical table top, given the laws of gravity and air resistance on a falling planar object, the bread flips, and only has enough time to flip once. Hence, it falls on the buttered side. Too bad.... *shrugs*

When dropped from a certain height (about table or counter height) it will usually fall butter side down because, as twinkle mentioned, bread has time to flip only once before it hits the floor. If you hold a piece of bread flat with the butter side up about a meter from the floor and drop it without tilting it, it will pretty much always hit butter side up; but in real life one side of the bread drops first as it slides off a plate or table or out of your hand, which causes it to flip over.

If you drop buttered toast vertically from a great height, it will actually land butter side UP more often than not! This is because the buttered side tends to be concave while the other side is slightly convex, and aerodynamics offset the difference in weight enough to tip the bread butter side up slightly more than half the time (this was shown through experiments done on a show called "Mythbusters.")

hmm...karma?

It only seems to do this. You are more likely to remember events with a negative outcome (e.g., scraping guck off the buttered side), than to remember those with a positive outcome (e.g., shaking a few bits off the slice and counting yourself lucky).

The CG of the slice of bread will have little effect on the outcome of the fall, because of the very short drop. Far more significant is the way in which you were holding the bread and the forces acting on it when it left your hand, particularly if you struck it in mid-air while cursing yourself.

Anyone out there volunteer for floor-cleaning duty if we undertake a scientific study of this phenomena?

It doesn't. It's just the way you dropped it.