You've probably seen this goofy desk toy bobbing away at someone's office: a colorful bird that dips its beak into a glass of water, then rocks back upright, over and over again. It looks like magic, or maybe a scam. But the Drinking Bird is actually a clever demonstration of thermodynamics disguised as a novelty item.

Invented in 1945 by Miles V. Sullivan, the bird works through evaporative cooling—no batteries required. The bird's head is covered in fuzzy felt that soaks up water. As that water evaporates, it cools the head, causing the liquid inside (usually methylene chloride) to condense. This creates a pressure difference that pulls the liquid up into the head, making it top-heavy enough to tip forward. When it dips, the liquid flows back down, and the cycle starts again. It'll keep going as long as there's water to evaporate.

What's brilliant is that it fooled people into thinking perpetual motion was real. Scientists loved using it to teach thermodynamics, while others just enjoyed watching the hypnotic bobbing. The toy even made a cameo in "The Simpsons," where Homer used one to press a keyboard key for him at work. While it's definitely a daft invention in terms of practicality, it's secretly one of the smartest toys ever made—proof that the best gimmicks have real science under the hood.