Fair play, I didn’t know the origin of it.If I may be allowed a little pedantry, Latin "cis" meant "on this side of".
The Romans were conscious of the Alps as a barrier, so they often used the term "cisalpinus", --on our side of the Alps.
This was in contrast to transalpinus, or transmontanus, referring to the far side of the Alps.
I have absolutely no idea what it means in terms of sexuality today.
But yeah, I’ve no idea what it means today, and I’ve no desire to. It seems very popular among all the useless people these days.