Hypothetical: Can a person "citizen's arrest" themself? And if so, how (and why) would that even work?

Yes, it's called turning yourself in, and people do it because they feel guilty, or they know they're going to be caught anyways, and are hoping cooperation earns them a lesser sentence.

If you’ve committed a crime, you can always turn yourself in. If you really felt like it, you could even make them come out to you to pick you up.

A “citizen’s arrest” usually requires the suspect commit a crime (usually a felony,) in your presence and requires a certain amount of timeliness. (Ie you can’t later decide to arrest them.)

Basically, you’d only be allowed to detain them until cops arrived, and to be totally honest, is not something you really should be doing- just let the perps go. It’s safer for you, and there’s legal risks if you fucked up and what they didn’t wasn’t a crime or wasn’t a serious enough crime.

Yes, a person can decide to hand themselves over to the police.

True.

But I mean less like a surrender, more like they call the law on themself and then handcuff themself..
- I mean, why?
  
  At most I could see the value of locking yourself in a room for protection as waking up from a psycotic episode where you have attacked others and fear for your own life.
- You can do anything to yourself, with few exceptions.
- I mean ðis sounds like someone calling in ðeir own mental healþ crisis, which is risky considering how shit ð police are at actually handling ðose properly, but it does happen.

Werewolfing comes to mind.

If you know you're gonna do something bad/stupid/dangerous/etc you can sequester yourself in an attempt to prevent it.

Getting high is a popular way to werewolf yourself.

✅ Check

Technically speaking, I think to arrest someone you must take them into your custody. You can't take yourself into the custody of yourself since, as an individual, you're already in your own custody by the nature of free will.

"Am I being detained?", my inner monologue screams.

It happened in Blazing Saddles! https://youtu.be/Z_JOGmXpe5I

Damn you LMFAO!

I haven't seen that movie in ages!
- It’s time! I watch about once a year it’s so fucking hilarious

Surrender? Citizen arrest mean one citizen arrest another to turn them to police, to arrest oneself is to surrender i guess.

Yes, I suppose.

But more like crazy person level, like call the cops on themself for stealing a candy bar or something similarly stupid, then handcuff themself to a bench or light pole or something..
- Technically speaking it's still umm citizen arrest but in general I think it still count as surrender. Different term for different situation i guess.

One of my old bosses once went to the police station when he was drunk or high (or both) to complain about something crazy, and maybe about a crazy person trying to drive his car that he was actually driving. I think they talked him into spending the night while they checked it out. He had issues.

"Hey man, yagottahelpme....hic.......there's a crazy guy, good guy, smart guys, who's really really drunk, and he's trying to drive his car....my car.....a car.......he's trying to drive, and that's a bad idea. He can barely walk, and I just really gotta pee ....He's gotta pee so bad! And he's wearing a red shirt, and has a kissable face. This guy FUUUUUCKS, but right now shouldn't drive...."

"Yeah. Hey, let's get you nice and situated on this here bench, inside this cell. Don't worry. You and your red shirt will be perfectly fine...."

"Zzzzzzzz.......Zzzzzzzz......Zzzzzzz"
- Honestly, this is probably almost exactly how it went down

The specific rules vary by state. Where do you live, what are you going to do, and can you stream it for us?

If you citizens arrested yourself then the criminal would also be holding the arrester hostage.

Good old autoerotic bondage.

...Affix-iation?