A neutron and proton enter a bar for a drink. The proton approaches the bar and orders a beer. The bartender says, "We don't serve electrons here."
The proton protests, "But, I'm not an electron, I am a proton."
The bartender asks, "Are you sure?"
The proton replies, "Yes, I'm positive."
And then there's the one about the engineers debating the nature of God.
"God must be a mechanical engineer – look at the human skeleton and how it works so perfectly."
"No," says another, "God must be An electrical engineer. Look how wonderfully all of the electrical signals route from the brain to the rest of the body."
"No," says the third. "He has to be a civil engineer. Who else would run a sewage line through a recreational area?"
Four engineers are driving along when the car starts misfiring badly. They pull over, pop the hood, and listen to the engine making bad sounds.
"Surely four engineers can figure out how to make this thing run well again" they said to themselves.
The chemical engineer said "I think it has water in the fuel tank. We need to change out the gas."
The electrical engineer said "No, I think the points are shot. We need to give it a tune up."
The mechanical engineer disagreed as well and said "I think we need to adjust the valves."
They then looked at the software engineer and asked, "Well, what do you think we ought to do?" He paused very briefly and said "I think we ought to just turn it off and back on and see if that fixes it." (insert groans here....)
Surprisingly, that very solution actually saved me one day. My Chrysler Concord had a flaky transmission that one day got stuck in first gear (not good when you're 25 miles from home). When I shut off the car and restarted it I was back to highway speeds.
This kept working many times over the next several weeks until the tranny finally crapped out (the car was not worth fixing). My transmission expert friend told me that when the car's computer detected errors from the transmission sensors it would tell it to go into "limp home" mode (i.e. the relative safety of 1st gear). Power cycling the car would clear the error and I'd be good to go until the next error code came along.