Poking around at the front part of the nail that's not attached to skin, I notice that there's a small bump like there's gunk under my nail. "Hm", I say, "Looks like I got some gunk under my nail." I try to just scrape the gunk out with another finger but it won't move.
So I get some tweezers, grab the bump, and pull.
Oh. My. God.
Turns out the "gunk" was a thorn, about 1/3 of an inch long. How it got under my nail I don't know. It might not seem like much, but it felt like a steel spike as it came out from under my fingernail. My finger still hurts and is a bit throbby.