Is there anything wrong with stepping on eggshells? Someone told me they think its wrong. Is it and why?

The Alter Rebbe brings from the Gemara that one should not step on egg shells because it can cause leprosy.

Although many of these types of things are not brought in Shulchan Aruch and other Poskim, this one is quoted by the Alter Rebbe.

There is also a story recorded of the Rebbe Maharash telling someone not to throw out egg shells in a area where people may walk.