This classic joke never gets old! Why did the chicken cross the road? To get away from the farmer's constant 'egg-xpectations'!
A doctor walks into a bar and orders a beer. The bartender looks at him and says, 'You're not going to believe this, but I'm a doctor too!'
A man walks into a library and asks the librarian, 'Do you have any books on Pavlov's dogs and Schrödinger's cat?' The librarian replies, 'It rings a bell, but I'm not sure if it's here or not.'