It may seem creepy to some, but I didn't read it that way. It's a fairly common and old phrase (the wiktionary entry is over 10 years old) and to me it doesn't have any sexualizing connotations, or other connotations I'd associate with being creepy. I'll grant you that it's vulgar, but do you see it as any creepier than any other vulgar phrase?

I agree that finding a group that accepts you is awesome. But I think that it's very valuable to improve your social skills with the default group. An issue I had (and have observed others having) is that, by spending time online, I would get used to making jokes and comments and references that online-people understand and appreciate. Then, I would do the same thing in real life and it wouldn't work. And people would talk about things that I didn't understand, like sports and popular artists, and I would feel left out. (Sports was the worst for me, because I grew up without cable so I had no way to keep up with sports even if I wanted to.)

I would guess this happened to OP as well. I think for most people that this happens to, it's not some unchangable quality they have, but just something that happens when to people who spend too much time in one social group and then abruptly move to an entirely different social group. (Someone who spends all their time with, idk, mormon lawyers, and then goes to hang out with blue-collar workers in brazil, will probably have the same experience,) 

I'm not saying that this replaces the need for finding a real-life group of people like yourself. Just that being able to fit into the default group when you need to is valuable and probably achievable with some effort. 

I just checked on my phone right now, and if you browse to En, the default Android Chrome browser both does not show you the https [...]

The behavior is slightly different for http sites. In that case, it shows an alert sign in the URL bar. In my opinion, that's actually a better way to do it than expecting users to notice the missing s . In this case it's still easily overlooked and your other attacks stand, especially vandalizing the page just before you pull off the stunt.

There was a recent post titled "Spaced Repetition Systems Have Gotten Way Better": https://domenic.me/fsrs/

It mentions this:

But what’s less widely known is that a quiet revolution has greatly improved spaced repetition systems over the last couple of years, making them significantly more efficient and less frustrating to use. The magic ingredient is a new scheduling algorithm known as FSRS, by Jarrett Ye.

I was skeptical, but I tried getting into spaced repetition again and I can say that the FSRS algorithm feels just magical. I often find that I'm just barely able to recall the other side of the card, which is exactly the goal of spaced repetition software. And in general, it doesn't feel like it wastes my time nearly as much as older scheduling algorithms did. 

An anvil problem reminds me of a cotrap in a petri net context. A petri net is a kind of diagram that looks like a graph, with little tokens moving around between nodes of the graph according to certain rules. A cotrap is a graph node that, once a token leaves that node, it can never renter. (There are also traps, which are nodes that tokens can’t leave once they enter.) My analogy: “having at least one anvil” is a cotrap, because once you leave that state, you can’t get back into it. So if you’re looking for a new term, cotrap is what I would suggest.

Thanks, this is a beautiful explanation

For math I'd like to submit this series: "A hard problem in elementary geometry" by fields medalist 
Timothy Gowers. It's a 6 part series where each part is about an hour long, of him trying to solve this easy-seeming-but-actually-very-difficult problem. 

"It's the only thing that satisfies my compulsion" is a good reason to do something IMO. Certainly not useless for you (even if it would be for most people), assuming it actually is the best thing you could be doing with your time that satisfies your compulsion. I definitely relate though, I find it very difficult to prevent myself from writing. 

what are the actual criteria you're using to evaluate them right now?

What I'm trying to get at is "how much does this hobby make my life better outside of me finding it fun". I think the two that come most to my mind are whether the hobby causes you to make friends and whether it keeps you in good shape, but those are pretty surface-level and obvious. There are lots of other ways a hobby can be helpful (e.g. it can advance your career, it can fulfill a desire in you to help others, it can make you money). But those all seem like saying "good books are ones with a relatable main character and narrative tension", they will help filter out many bad (and a few good ones) but they're to simplistic and general to be much help in finding a truly great one. Many great books are great because they did something unique no one else did, and probably many great ways to spend your time are great because they have some unique massive advantage that's difficult to find anywhere else. 

The way I think of it, is that constructivist logic allows "proof of negation" via contradiction which is often conflated with "proof by contradiction". So if you want to prove ¬P, it's enough to assume P and then derive a contradiction.  And if you want to prove ¬¬P,  it's enough to assume ¬P and then derive a contradiction. But if you want to prove P, it's not enough to assume ¬P and then derive a contradiction. This makes sense I think - if you assume ¬P and then derive a contradiction, you get ¬¬P,  but in constructivist logic there's no way to go directly from ¬¬P to P.

Proof of negation (allowed): Prove ¬P by assuming P and deriving a contradiction

Proof by contradiction (not allowed): Prove P by assuming ¬P and deriving a contradiction