Well, we're planning to watch the super bowl in an hour and half. It would be pretty noticeable if all men were gone.

I would notice pretty quick when I'm not being catcalled on my way to work

They turn into the failed Ripley clones from Alien Resurrection.

Intersex people don't vanish.
If you yourself are intersex, nobody vanishes for you.
Trans People vanish based on their passability for the opposite sex, if they're androgynous they don't vanish.
If you yourself are trans then the opposite of your prefered gender vanishes.

Check one of my other answers to the comments.

Yeah this seems to be a question for mainly people living alone... I'd notice within the hour.

But like sex and gender are social constructs

Honest response here, no hate intended: I thought gender was a social construct but sex is biological?

Ditto. I'd have so few friends, not to mention my wife and daughter (no males in the house other than me) so things would be pretty confusingly lonely, pretty quick!

At least OP was pretty clear that all people of the opposite sex were to have disappeared so I can still have my dog.

They go in a quantum state, existing and not-existing at the same time until someone perceives them, at which point they go into one of the two quantum superpositions: being or not being.

Or nothing would happen, idfk.

Where TF did my entire family go??

Immediately, I don't have any same-sex spaces or activities. I guess if I was in the bathroom at work it might take a couple of minutes.

I would miss sex so much, but car insurance would go down and a lot of the crime. Eventually everyone would notice though if all the males were snapped out of existence because there just would be as many people.

Could be worse, I'm intersex. I'd be totally alone, except for, like, maybe other intersex people?

No SO, but I'm trying. Since "people", I'll see my dog, that part is normal. I'll be quite worried and anxious if the psychologist I'm talking to would suddenly become out of contact, especially when it's usual weekday and time.

I'll definitely become agitated and will run around looking for my mom.

I'll be scared for every girl I've cared about who won't be online since a certain moment.

But due to self-gaslighting, I'll likely wait for a few days before assuming that things are very wrong.

I'm. Non-binary of the binary non-binary and binary, so I'm non binary squared