u/27onfire

Three guys walk into a bar.. a biologist, a physicist, and a mathematician.

​They’re sitting by the window when they notice two people walk into the house across the street. A few minutes go by and suddenly, three people walk out.

​The biologist says, 'It’s simple! They reproduced.'

​The physicist shakes his head. 'No, no. Our initial observation was clearly flawed.. there’s an error in the measurement!'

​The mathematician looks at the house, sighs, and says, 'Actually, if exactly one person goes back into that house, it will be empty again.'