Family Math

Teacher: If you had one dollar and you asked your father for another, how many dollars would you have?
Vincent: One dollar.
Teacher (sadly): You don't know your arithmetic.
Vincent (sadly): You don't know my father.

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The female dormitory

The female dormitory will be out-of-bounds for all male students, so too the male dormitory to the female students. Anybody caught breaking this rule will be fined $20 the first time. Anybody caught breaking this rule the second time will be fined $60. Being caught a third time will incur a hefty fine of $180. Are there any questions?"
At this, a male student in the crowd inquires, "Er... How much for a season pass?"