I used to be a banker.

This tidy one-liner is a masterclass in wordplay, banking on the double meaning of a single key term. The humor comes from the pun built around the word "interest." On one hand, it refers to the common feeling of being engaged or enthusiastic about something. On the other, it's the fundamental concept in finance: the money you earn on savings or pay on a loan. The punchline forces a delightful collision between these two meanings, taking a mundane reason for quitting a job and giving it a professional, industry-specific twist.

The joke also gently pokes fun at the stereotype of banking as a somewhat dry or monotonous profession. It’s funny to imagine someone so surrounded by financial "interest" that they end up losing their personal "interest" in the whole affair. By blending a very human, relatable feeling with the core jargon of the industry, the joke cashes in on a simple but brilliant connection that is guaranteed to earn a laugh (or at least a good-natured groan).