A mathematician, biologist and physicist are sitting in a street cafe watching people going in and coming out of the house on the other side of the street.

Posted by nothinlefttochoose@reddit | Jokes | View on Reddit | 37 comments

First they see two people going into the house. Time passes. After a while they notice three persons coming out of the house. The physicist says: "The measurement wasn't accurate." The biologist concludes: "They have reproduced." The mathematician says: "Now if another person enters the house, it'll be empty again."