Shamelessly lifted from reddit:
A physicist, a biologist and a mathematician are sitting outside of a bar when two men walk into the house across the road…
Ten minutes later, three men walk out.
The physicist looks confused and says “There must an error in the measurements.”
The biologist retorts “No, they must have reproduced!”
To which the mathematician says “If one person goes inside, the house will be empty.”
An oldie, but a goodie:
An optimist will say that a glass is half full.
A pessimist will say that the glass is half empty.
An engineer will say that the glass is twice as big as it needs to be.
The physicist will point out to them that they are all wrong, because the glass is quite full: half with liquid, half with air!
And why not pick on engineers a bit:
Three professionals, a mathematician, a physicist and an engineer, took their final test for the job. The sole question in the exam was “how much is one plus one”.
The math dude asked the receptionist for a ream of paper, two hours later, he said: I have proven its a natural number
The physicist, after checking parallax error and quantum tables said: its between 1.9999999999, and 2.0000000001
The engineer quickly said: oh! its easy! its two,…. no, better make it three, just to be safe.
And a bit more:
During the French revolution a priest, a drunk and an engineer are sent to the guillotine. They ask the priest if he wants to face up or down when he meets his fate. The priest says he would like to face up so he will be looking towards heaven when he dies. They raise the blade of the guillotine and release it. It comes speeding down and suddenly stops just inches from his neck. The authorities take this as divine intervention and release the priest.
The drunkard comes to the guillotine next. He also decides to die face up, hoping that he will be as fortunate as the priest. They raise the blade of the guillotine and release it. It comes speeding down and suddenly stops just inches from his neck. Again, the authorities take this as a sign of divine intervention, and they release the drunkard as well.
Next is the engineer. He, too, decides to die facing up. As they slowly raise the blade of the guillotine, the engineer suddenly says, “Hey, I see what your problem is …”
Xanthippa's Chamberpot 