A really long line of mathematicians are queuing up outside a bar.
The first one enters and asks of the barman, "Can I have a pint, please?"
The barman pours it, and the first mathematician takes a seat.
The second mathematician in the queue then enters, and asks of the barman, "Can I have a half-pint,
please?"
The barman pours it, and the second mathematician goes over to sit beside the first.
The third mathematician in the queue then enters, and asks of the barman, "Can I have a quarter-pint, please?"
The barman says "Just this one time", pours it, and the third mathematician sits beside the first two.
Then the fourth mathematician in the queue enters, and asks of the barman, "Can I have an eighth of a pint, please?"
The barman looks at him and says "Look, go outside and tell everyone in the queue to come in at once." Then he pours two pints!
AMIRITE!!