It occurred to me to wonder where the line is that you don't cross with very close friends.
I have two best friends, both gay, with whom I can talk about most things.
One is a little less open than the other.
The most open one I actually had sex with about 12 years ago. Just the once.
Since then we have done quite a few things which you can only do with your very closest of friends.
For instance, today I shaved him. He was naked and on his hands and knees while I shaved his asshole and then moved on to his pubis.
In the past I have given him a rectal exam when he feared he had medical problems and I have also examined his penis when he was worried he had an STI
My other friend I would not contemplate even seeing him naked let alone examine him. Although we did used to be in a gay sauna (bathhouse) at the same time but carefully avoided each other.