What makes Trans people think they get to call me "Cisgender" when I don't accept the term?

Cisgender is just a descriptive term meaning the opposite of transgender, ie. someone whose gender identity and physical sex are the same. Whether you accept the term or not (and nobody's saying you have to), if you are not transgender then by definition you are cisgender. Your objection is as silly as someone who's right-handed rejecting the term when left-handed people call them right-handed.

I believe that cisgender just means straight. No big deal.

Exactly where does a transperson come up to you and address you as "cisgender"?

Trannies are continually trying to impose language on others.

They learn these bullying tactics from their "gender therapists" and other highly-paid "professionals" who brainwash them into thinking it is possible to change their birth sex.

And most of them only mix with other radical trannies who all echo the same language fascism.

Maybe you should look up the definition and expand your vocabulary .

Well, cisgender is just a word meaning not trans, so it's just what is said? Since imo it would be kind of tacky to say "not trans" all the time, when there's a perfectly valid word for it out there. I won't deny it does seem to have a bad connotation because of all those "down with cis" jokes and all, but I don't think anyone says that seriously, and if there were another term for it without that association I'd probably use it instead.

The difference between a trans woman not wanting to be called male and a non-trans person not wanting to be called cisgender is that in the first case what they're being called goes against their identity conceptually, while in the second case the word still is in line with how the person identifies, even if it's a term they don't care for.

It is very rude of them to use that sort of language about us.

they tried to say i was born cisgender but i was born a male no one is born anything but male or female

In Latin "cis" is the opposite of "trans." So calling you cisgender simply means that your gender identity matches your biological sex. That's like getting upset because someone is calling you "right handed" when you prefer to be called "not left handed."

You don't have to use the term, but you can't prevent other people from using it.

It's that simple.