Complex things.

As a general rule, people are idiots. That is why whenever people are confronted with something so complex that they can't comprehend, they make things up. I'm pretty sure this is why there is religion. Religions have arisen to explain the enormously complex planet that we live on and what happens once we stop living on it. For example, try and imagine being dead. It is impossible, we simply can't comprehend it. You'd have no feeling, no sensations, no memory and no thoughts. We just can't imagine what it would be like. This scares some people, because let's be honest, unknown things can be scary. That is why people have invented the afterlife, so they can imagine what it is like to be dead, even if it isn't true, it is comforting. There are other aspects of religion that have been invented, because the scientific answer or reasoning is too complex for people to comprehend. Evolution is pretty complicated so for convenience people have invented creationism.

Religion isn't the only example of people making things up when things become complex. There are many superstitions and habits that people do, just because something good happened the last time they did it, or something bad happened when they didn't do it. There is a fine line between superstition and doing something for a reason. For example, washing your hands before performing surgery is something that every surgeon does, but not through superstition. Finding a four leaf clover is considered lucky, but it isn't, they are just uncommon, so this is clearly superstition. However if you do something superstitious often enough so it becomes a habit, it can actually have a positive effect on you. For example if you are getting kitted up for a sports match and get dressed in an order unusual to you then you might feel uncomfortable and not play as well. It is really just what your brain associates with said superstition.

Most superstitions come about because of coincidence. There are so many things going on at the same time across this vast planet that there are bound to be coincidences. Often these coincidences are mistaken as something mystical and become superstition.

So sorry, but those lucky pants you have aren't really lucky, it was just a coincidence.