This one’s usability depends on your headcannon: how scared normal fluffies are of alicorns? If not, you can go read more interesting posts.
But what if they are? Then you can use that for some fun with a stray herd. First of all, you need to get them into a small room (an empty chicken coop, for example).
Next, you give them sleeping pills and, while they are asleep, glue fake wings and horns to all of them. You have to be quick and quiet to finish before any of them wake up.
Once the deed is done and they start waking up, the chaos will start. The herd will wake up once one of them notices something’s up and starts screaming. What each and every one of them will see is that it is surrounded by “munstahs”.
Some will lie down and cry, a couple may try to “give sorry hoofsies”, some will try to get out, some will just run around in panic, and all will shit all over each other. And you, the mastermind, will enjoy the show.