I used to work at a calendar factory

This joke hinges entirely on a delightful bit of wordplay, specifically a pun that plays with our expectations. The setup about working at a calendar factory perfectly primes the audience for the punchline. When you hear about someone getting "fired for taking a few days off," your mind immediately jumps to the common workplace scenario of an employee being disciplined for unauthorized absence or using up their allotted vacation time. It's a relatable, albeit serious, work issue that many people have encountered.

However, the genius lies in the double meaning that the calendar factory context provides. In that specific setting, "taking a few days off" transforms from an employee benefit or infraction into the literal act of physically removing pages – the actual 'days' – from the calendars being produced. This absurd, literal interpretation is what delivers the laugh, playing on our initial assumptions and twisting a familiar phrase into something entirely unexpected and silly. It’s a clever linguistic trick that turns a common workplace phrase on its head.