I used to hate facial hair, but then it grew on me.

This clever one-liner hinges entirely on delightful wordplay, using common phrases with dual meanings to create a humorous surprise. The setup, "I used to hate facial hair, but then it grew on me," immediately introduces this linguistic trick. The phrase "grew on me" literally describes hair sprouting from one's face, but colloquially, it means someone gradually came to like something they initially disliked. This dual interpretation is the engine of the joke, creating an expectation that is then playfully subverted.

The punchline, "Now I'm quite attached to it," further capitalizes on this double entendre. "Attached to it" physically refers to the hair being connected to the skin, but it also means having an emotional fondness or strong liking for something. The humor comes from the audience's realization that both meanings are true simultaneously, creating a relatable scenario for anyone who has ever contemplated growing or styling their facial hair. From ancient civilizations where beards signified wisdom or status to modern trends of various styles, facial hair has always been a personal statement, and people's feelings about it can indeed evolve over time, making the joke's premise universally understood.

This joke's charm lies in its conciseness and the unexpected twist of familiar language. It's a classic example of a one-liner that relies on the audience's quick grasp of idiom and literal meaning, delivering a satisfying chuckle through its simple yet ingenious construction. It pokes fun at the common experience of changing one's mind, all while celebrating the literal growth of a good beard or mustache.