I graduated High School in the 2000s. And yeah I heard, “nah, thats gay” ALOT but its was almost always in reference to things boys didnt want to do cause they thought it would make them look gay if they did it. ie.

Kid A: “Hey you wanna join Marching Band.” Kid B: “Nah that’s gay.”

Kid A: “Do you want to go watch an off broadway productiong of RENT instead of playing Halo?” Kid B: “Nah That’s gay”