It is thought by many that there are monks in china that once practiced walking through walls. There was an incident where it was found that a human body was stuck in the middle of a concrete wall. This was explained by the monk practicing his walking through walls and then lost his concentration while he was inside and was unable to continue walking. The monks molecules were intermixed with the molecules of the wall.

I believe this was remembered from an old discovery channel show.

As far as physics is concerned when you get close enough to a nucleus things start to attract again despite them being the same charge. This overwhelms the repulsion normally found from opposite charges. This is how the neutrons stick together in the center of an atom. What exactly this has to do with walking through walls I'm not exactly sure, but I think someone will be able to figure it out. I'm just a lowly computer science major.