I found this in another forum:
A neutron walks into a bar and asks: “Hey, how much for a beer?”
The bartender says, “For you, no charge.”
Two protons are sitting in the corner, watching. One turns to the other and says, “Hey, that neutron got a free beer!”
The other replies, “Are you positive?”
A neutrino enters the bar and joins the other particles, looking very down in the mouth.
“What’s up with you?” asks the neutron.
The neutrino sighs and says, “I’ve just been kicked out of church.”
Shocked the others demand, “What for?”
“Apparently,” replies the neutrino, “I’m not supposed to have mass.”
Two grumpy quarks walk into the bar.
One says to the bartender, “I’ll have a double bourbon, straight, and my bitch here’ll have his usual Miller Lite!” and slaps the other quark hard on the ass.
The neutron leans over to the protons and whispers, “No need to guess who’s the top and who’s the bottom.”
Three hot electrons and a shiny photon enters the bar.
The bartender says, “Stuff this, I’m getting the manager! Hey, Pauli, we got a problem!”
Suddenly this huge Italian appears and tells all the particles to leave. When they start complaining, he yells “This is ‘Pauli’s Bar’ and I’m Pauli! If I say ‘no particles’, then it’s no particles! Get out, you’re all barred!”
Grumbling, all the particles leave the bar. Except the photon, who walks straight past Pauli and orders a drink!
“Hey!” says the bartender, “What about him?”
Pauli glances over to the photon, “Nah! That don’t apply to him!”