I've been sort of crabby lately. It's that time of the month again–the rent's due.

The line is a joke built on misdirection. “That time of the month” commonly cues a reference to menstruation and mood changes; the punchline pivots to a more universal irritant—financial pressure—by revealing that the speaker’s “crabby” mood comes from rent being due. The humor depends on collapsing a gendered cliché into an economic reality, suggesting that money stress can be as cyclical and predictable as any biological calendar. It also lightly critiques how readily people reach for stereotyped explanations for irritability, while implying that material conditions (bills, housing costs) are often the more immediate cause.