It'll get eaten.
You're probably thinking yeah, duh. But I've got an interesting story about this:
I accompany my mother to the grocery store about every other day and while we're in the bread section, she'll usually ask me if I want something as she's getting her own pastry (some maple syrup and walnut thing that I find disgusting). One day, I got a donut: a nice chocolate glazed one with chocolate filling that I didn't know about and was wary of (Starbucks muffins have a similarly colored filling, but it's hazelnut, which I despise).
Having just had breakfast before, I didn't eat it right away. Instead, around 12h, while lunch was being prepared, I cut a quarter of it and scarfed it down. Normally, I would have eaten the rest after dinner, but I'd just baked a cake (the one where the butter was refusing to cooperate) and I had a bunch of that.
The next day, I ate another quarter of a donut when I felt like chewing on something. Again, I didn't eat the rest, because there was another cake to eat.
The day after, my mother reminded me the half donut was still there, just waiting to be chewed up and swallowed. I had another quarter. I wasn't baking that day, but I was rather miserable, as the telly wasn't working, and the water refused to warm up despite turning it to the maximum setting. It was only later that I'd discovered that the building people had decided to change the boilers that day (no notice whatsoever! And the bathroom was steamed up after my Dad's shower that morning!). I had to go to bed with greasy hair and it was terrible.
Then yesterday, I'd forgotten all about the donut, because we'd gotten back to baking. I'd forgotten to post pictures of it, but it wasn't amazing. It was awfully dry, because my mother had suggested we cut down on the butter after the last one turned out super greasy (which was my fault. Read about it here). Thanks a lot, Mom.
And today, I was wandering about just before dinner time, waiting for my father to come back so we could eat, and caught sight of the last piece of donut. It was promptly eaten. It was awful. It was chocolaty, but hard, and sort of crumbly. Very odd.