Atom

Almost everything in the universe is made of atoms. Atoms are however roughly 99.99999% empty. Just think of atoms like very small clouds that overlap with lots of other tiny clouds.

It thus becomes very easy to shoot neutrinos, a subatomic particle with no charge, through humans. (Atoms contain protons and electrons which both have charges. If you were to shoot something with a charge at an atom, it'll either be attracted or repelled from the protons/electrons.)

Not even the Earth can stop neutrinos from going where they want to.