Probably one of the most mis-used word but the definition of a gay is: Attraction between people who are the same sex
Gay can be used to mean stupid or lame like if your phone is not working or if your car got stolen that would be a gay because it would suck. It can also be used to insult someone like if they do something stupid like brake there arm by jumping of a bridge they would be gay because they did something stupid.
“My phone is being so gay” “I crashed my car, how gay is that”