I'mma burn off the old brush and answer all three prompts.
1. "Forget existential dread: what's the most existentially exciting thing that's ever occurred to you?"
A two-week period from a couple of years ago comes to mind; right around the time we were wrapping up 'Adventures in Faking This,' a friend of mine (with a considerable internet following) was pitching a webseries to some internet-famous-person's production company, and it seemed like the stars were all perfectly aligned; the internet-famous-person was a fan of my friend, and also trying to get several webseries off the ground, and also a big fan of musicals — and my friend's pitch was for a musical webseries, incredibly-roughly-along-the-lines-of Glee, but... you know, a musical, not a jukebox. My friend asked me if I'd 1) act in it and 2) write the songs. In my newly-adopted capacity as Songwriting Person, the possibility of suddenly having a big springboard and audience for Songwriting Stuff — and serendipidously having an album ready to hock — was pretty exciting.
I (and Alex, on short notice, very helpfully) dove headfirst into a making little animated storyboard-and-song demo for my friend to pitch with; I wrote a little duet and blocked out storyboards for it, and sent my friend a version where I sung both parts, just to get friend's reaction — friend loved it. All that was left was to lay down my friend's vocals and let Alex finish adding instruments to it; for a couple days, right at this moment, it seemed like my future as celebrated-internet-music-asshole was in the bag.
Prior to this, I hadn't actually heard my friend sing — I just assumed, y'know, 'well, anyone intentionally embarking upon this project,' etc. — and it wasn't until we were laying down their vocals that I... found out.
The project died soon thereafter.
2. "What's the most amusing physical injury you've ever had?"
I think this may have come up before, but in addition to being a competitive 'trick' roller-skater for a while, I was also an alright-but-nowhere-near-competitive kneeboarder. A kneeboard is another one of those gets-pulled-behind-a-boat thingies, like wakeboards or water skis; in this case, you kneel on a big bullet-shaped board with a strap over your knees and go from side to side behind the boat, jumping off the wake, doing backflips and stuff. (It's the only time in my life I've ever had ab muscles. Unfortunately, it was also when I was at my heaviest, so I didn't get to see 'em.) Anyway, you can imagine the mechanics of a backflip pretty easily — come in screamin' sideways toward the wake, get as much air as possible, pull back hard, hope like hell that your board's nose doesn't get stubbed and bring you to a sudden thirty-mile-an-hour stop — but there's another spinning trick you can do, on the horizontal axis; that is, you can get into the air, spin a 360° — just like a top — and keep going in the direction you came. The mechanics of this one are a little weirder: the only way to get spinning fast enough is to abandon the handle, pull yourself forward on the rope five or six feet, wrap the line like a belt around your body, wind yourself up — just like a top — and then reclaim the handle with one hand while still holding the taut rope with the other, so you don't start spining immediately. Then, you go way out to one side of the boat, come in screamin' sideways toward the wake, and right as you're getting into the air, release the taut rope and hold onto the handle for dear life. Vvvvvwip! Works like a charm.
Except — remember that bit about making sure you complete a backflip, so your nose doesn't stub the water at a steep angle and bring you to an immediate stop? Well, this one time, I was doing one of those wrap-spin tricks, and for whatever reason I didn't pull my nose back on my approach to the wake, so instead of surfing over it, the nose of my board just went into it and, yep, I came to a very abrupt halt — with the rope still attached to the boat, and also still wrapped around my body.
The result was a two-inch-wide bruise that spiraled completely around my torso.
(I might have also broken a rib; it was never clear, but in retrospect it seems likely.)
3. "At what point did you realize that you, at some specific point, were no longer the same person you were at some specific point in the past?"
I hate to keep bringing this up, because it makes it sound like I'm always bringing it up (and I don't think it's come up in real life more than, like, twice, ever, lo these recent Star Warsy years), but: when I decided not to watch any more Star Wars movies. I very nearly didn't even see The Force Awakens, but of course I did; and then, that was it. Even the version of me as recently as at the end of WAYDM would have never, ever believed this was a possibility; Star Wars was just too much of my established personality to abandon, even if it sucked, and yet — life is weird — I abandoned the personality, and Star Wars went with it.
Smoking, drinking, caffiene; Star Wars, etc..
Life is long, so no proclamations — I may end up seeing 'em at some later date — but for the next few years at least, I think I'm more likely to become a furry than to give Star Wars the time of day, and that's the most-obvious personal evolution I can get a handhold on.
Has anyone ever saved your life?
You're afraid of something unusual; what is it, and how did you find out you were afraid of it?
Who somehow reminds you of a song? What [different] song somehow reminds you of a person?
What was your most-retrospectively-embarrassing prolonged fashion choice?
Obliterate one holiday, and invent one holiday.
I have a tendency to fix your typos.