I'm reading a book about the history of glue.

This one-liner gets its stickiness from a classic case of wordplay, specifically a pun. The humor hinges on the double meaning of the phrase "can't put it down." When we talk about a book we "can't put down," we usually mean it's so captivating and interesting that we're compelled to keep reading. But in this joke, the subject is glue, and suddenly "can't put it down" takes on a very literal, physical meaning—the book is literally stuck to you because of its subject matter!

Glue itself has a surprisingly long and fascinating history, dating back thousands of years to natural resins and animal-based adhesives. Humans have always sought ways to stick things together, from ancient Egyptian furniture to modern superglues. The very essence of glue, of course, is its adhesive quality, its ability to bind surfaces. This fundamental characteristic is what makes the joke's literal interpretation so perfectly unexpected and amusing.

The cleverness of the joke lies in setting up an expectation based on common idiom and then twisting it with the specific, sticky reality of the topic. It's a quick, clean punchline that relies on that sudden shift from metaphorical engagement to literal attachment, leaving you stuck on how brilliantly simple it is.