I am beginning to suspect that it is surprisingly common for intelligent, competent adults to somehow make it through the world for a few decades while missing some ordinary skill, like mailing a physical letter, folding a fitted sheet, depositing a check, or reading a bus schedule. Since these tasks are often presented atomically - or, worse, embedded implicitly into other instructions - and it is often possible to get around the need for them, this ignorance is not self-correcting. One can Google "how to deposit a check" and similar phrases, but the sorts of instructions that crop up are often misleading, rely on entangled and potentially similarly-deficient knowledge to be understandable, or are not so much instructions as they are tips and tricks and warnings for people who already know the basic procedure. Asking other people is more effective because they can respond to requests for clarification (and physically pointing at stuff is useful too), but embarrassing, since lacking these skills as an adult is stigmatized. (They are rarely even considered skills by people who have had them for a while.)
This seems like a bad situation. And - if I am correct and gaps like these are common - then it is something of a collective action problem to handle gap-filling without undue social drama. Supposedly, we're good at collective action problems, us rationalists, right? So I propose a thread for the purpose here, with the stipulation that all replies to gap announcements are to be constructive attempts at conveying the relevant procedural knowledge. No asking "how did you manage to be X years old without knowing that?" - if the gap-haver wishes to volunteer the information, that is fine, but asking is to be considered poor form.
(And yes, I have one. It's this: how in the world do people go about the supposedly atomic action of investing in the stock market? Here I am, sitting at my computer, and suppose I want a share of Apple - there isn't a button that says "Buy Our Stock" on their website. There goes my one idea. Where do I go and what do I do there?)
Say you go into Starbucks and there's a long line of customers waiting to order a drink. Approach the end of the line and go "Whoah, long line!". Chances are, you'll get someone's attention. People will turn around and look at you. When they do, make eye contact and say "We're gonna be here a while!" or something like that. You're immediately building rapport by referencing a shared context, as well as broadcasting your own confidence and willingness to socialize. It works great.
A more difficult scenario, but still quite doable, is a bookstore. Find someone reading a particular book or type of book, or looking through a certain section, and engage them on it. "Hey, good book!" They're looking through the psychology section? Say "Psshh, Descartes. What did HE know?" This sort of thing will elicit a smile from almost anyone. The important thing is to not LOOK awkward, even though you may feel awkward.
Yes, this approach is cheesy. And some people may find you annoying. But those are people who are likely annoyed with life in general. Overall, you can generate a lot of positive results this way. If you want to generate maximum socialization, be THAT guy.