gay as hell is actually a mathmatical term referring to the average gayness of all people sent to hell, it is especially high, considering that all priests go to hell
it is found by dividing the total amount of gays in hell by the total amount of people in hell, to find the average amount of gays in hell
This term is not usually in reference to someone who is a part of the LGBTQ community, but as an immediate and unthought-through expression that translates to "That is stupid"
Bro that llama spat on me now my shirt is covered in spit that's gay as hell.