(This question POSSIBLY Not Suitable For Work -- ) What would happen if I did this (see details) ?

Maybe it depends on the area of the country.

I suspect that where I live, probably nothing. A few months ago, there was a pickup truck in my area and it had painted on the back window “Trump 2020: Fuck your feelings.” Apparently the word “fuck” is not anything shocking to have out in public. Personally, I’m thankful that my daughter is a teen because if she was little, I’d not be thrilled to have her seeing the word “fuck” and possibly having to explain it, but I guess we should get used to seeing it in public.

Go ahead. It’d be an experience.

If there’s a bored officer, they may tell you to stop, and/or come people may complain. But I expect others would laugh / wave / honk or something.

In my place you would mostly be ignored for being crazy. Some bold people may come to you and shout the f-bomb back or a hurtful sarcastic remark. Some may want to pick a fight with you. A policeman may come to you and tell you to drop the act.

But the worst thing you should look out for is being secretly filmed. Your face would be all over the Internet. Best case scenario, you would become an Internet meme and no one would care who you are, as long as you look good for a joke. Worst case scenario, you would become a laughing stock or the target of fake news and conspiracy theory. Some people may even dox you based on what they see on the video, and before long you are bombarded with hate messages and death threats. You could come to the police but then again you were the one to start that in the first place, and it’s impossible to sue the Internet. After a while the Internet would die down and people would move on to another drama, but your name surely would never be completely forgotten, as people would bring you up once in a while during unrelated discussion.

Here you would probably be ignored for a couple of hours then the rain would come on and you would go home. Either that or someone with a kid would report it and the police would give you a warning. You could try spelling it FUKC. That seems acceptable.

You could stand next to the people holding signs in front of Planned Parenthood.
It would make an interesting meme for a few Instagram picture fans.

You would probably be arrested (or asked to move on) for creating a nuisance.

I don’t think that your sign would be any more offensive than the anti-choice people standing on bridges with their signs (happens in metro Atlanta). or the various Jesus Saves signs on billboards all over the place.

Some guys would be pulling over asking “How much?”

Possibly you’d be cited for violating some local ordinance about standing on the roadside while holding a sign without a permit or something, but probably nothing more.