A neutron walks into a bar...

thadnation

This one is a bit lame, but hey, it's not bad.

A neutron walks into a bar and ordered a beer. He asked the barman how much for his drink. the barman replied, "for you, no charge"

nivinjoy

brokenadvice

I think i heard this in science, and have never forgot that neutrons have no charge since.

Genesiz

We had this massive science test once, and me and my friends just turned all the facts and forumlae into jokes and songs (like this). You never forget them even now.

If this ever comes up in science, i'll just remember this joke, and probably have a laugh at the same time.