This won't be easy to hear... but unicorns fart.
I wish there was a way to help ease your mind into this new reality you find yourselves in, but I think in the end it's better to just blurt it out there. They fart. Unicorns fart.
And before you think, "Oh, but I bet their farts are cute!" or "They probably smell like peppermint mocha!" Going to stop you right there, because, no, they are loud, often, and smell like apples that crawled up a horse butt and died. If anything, unicorn farts are the least magical thing about unicorns.
Now... maybe I'm a little bitter about this topic. Could be because I spent an otherwise nice evening transfigured as a shrub in the Forbidden Forest near Hogwarts hoping to catch some unicorn hair as they pass by for my studies in wandlore and wandmaking. A truly magnificent stallion came through the meadow, began grazing ever closer to where I'd planted myself... and then proceeded to fart in my face on an off again for over an hour. I think muggles call it "crop dusting."
And I couldn't do anything. I couldn't laugh, I couldn't move... to do either might break the transfiguration spell. And you need to not be human around unicorns - they are deadly... not to mention silent but deadly, also. Legend says a unicorn would accept the company of a pure, unsullied maiden. Ha! I'm a Slytherin, so I'm not testing that legend out.
The only interesting thing that is worth me writing about farting unicorns is something I observed... they're self-conscious about it. And that's actually kind of adorable. If other unicorns are around and it happens, everyone's head goes up and then the one who farted points his horn at another unicorn and much neighing denials and snorts of derision follow. Actually I saw a lot more fart blame pointing with the unicorn's horn than any other purpose for it, so maybe that's why they have a horn in the first place?