When Luke goes into Leia’s cell on the Death Star to rescue her, her first line to him is, “Pretty short for a Stormtrooper.”

As a joke explainer / ruiner, it’s the misdirection of the punchline makes you think it’s going one way then delivers a line from the movies, which was a joke line. Don’t mind me, I’ve been dissecting language lately to see what make what’s work. I haven’t got as far as I’d hope for living this many years.