looking for this horror movie if anyone knows it

ok this thd only thing that i remember from it since it was from a small snipet on tt is that its from 80s-90s about two friend and they were at camp and theres a killer but the plotwist was the killer is the girl i think then turns out she wasnt a girl but a guy from what i remember

Im so desperate to find this cuz its quite a good movie and the plot is also good