I'll admit I have a mischievous streak. Because of that, I've had my eye on a TV-B-Gone for a while now. A company called Cornfield Electronics makes the gadgets, which come in a few different shapes and sizes, and all of them serve a single purpose; to shut down almost any screen that is controlled by a remote.
After months of convincing myself I didn't need one, I decided to place an order for the TV-B-Gone Pro SHP. The "SHP" stands for "Super High Power," and the device has a claimed range of up to 100 meters. It also happens to look like an older model iPhone, so you can use it in public without anyone suspecting a thing. Pressing the mock "Home" button prompts the device to begin cycling through dozens of remote codes, giving it the ability to power down many, many displays.
As the name would suggest, it's primarily targeted at TVs, but as the gadget runs through its long list of remote codes it also hits on the ones Apple uses for the Apple remote. This means it'll put Macs to sleep as well, and it worked splendidly with both my Mac mini and MacBook Pro. Essentially any newer Apple product with an IR port is vulnerable, meaning that you could turn off an entire coffee shop's worth of MacBook Pros with a single button press.
If you work in an office full of Mac users, you could have some fun with this. I haven't personally tested it out on anyone poor soul's shiny Apple laptop in public, but the temptation is definitely strong.