How do you react when people laugh at your tics?

That's an absolutely valid way to feel about it. I also get very offended when strangers laugh at my tics, and it would annoy me a little if my friends did too, but it all depends on your boundaries and your feelings.

It's pretty circumstantial for me. If the person has tics I'm comfortable with them making jokes about it. If they don't even though we're friends it's still kinda weird. If I don't know them and they don't have tics I don't like it when they comment on my tics. There is the exception of if it's something explicitly funny (like I jocular vocal tic or a motor tic with perfect comedic timing).

It also depends for me. If I'm friends with the person, or have at least known them for a while to the point I'm comfortable with them, I say they can laugh and make jokes. Because hey, sometimes it's funny. It's hard to say it's not. Sometimes I bark at nothing, or make a really weird sound, or say something odd. One time at work I was talking with my manager and my friend (who also works there) and had been hitting myself in the chest. They were both ignoring it since that kind of thing was normal. Then I smacked myself in the throat-- choked, wheezed... and we all burst out laughing. I genuinely found it hilarious, because I wasn't hurt, and I was comfortable with those people. My friends and co-workers joke with me, unless I seem genuinely distressed about it, or if it's a bad tic day (I've worked there for like a year now, I'm pretty established with people.) In which case they treat it like it's nothing and are chill about it. If a stranger were to make a joke after seeing me ticcing, I'd be more put off, and probably pretty uncomfortable-- unless it were somebody else who had a tic disorder. They could relate and I'd know it's from a place of understanding. But otherwise, I don't know their intent, and they don't know me. But like you said, it's to each their own. If you're fine with joking with your friends, that's cool! Friends tease! And as long as it isn't crossing boundaries, and you don't feel upset, then great! The people who don't know you very well shouldn't be making those jokes if it upsets you, though. And you've got every right to make that point. Do what makes you comfortable :)