Two friends that are comfortable with each other to do anything and talk about anything. This is very close to an open relationships the only difference is that you are not labeling it as a relationship.
A comfortable friends is someone you can feel 100% yourself around them. the first thing the pops into your head you can say or do around them and they can to you. you are never weirded out by them and vice-versa.
often time relationship can be 'down-graded' to Comfortable Friends status. since Comfortable friends status give you to the joy of thier company in the same way as the relationship (the physical and the emomtional aswell as the stupid hanging outs) without the preasure or stigmas of beinging in a realtionship.
I get along with this one guy so well, but I don't want to be tied down so we are comfortable friends
"are you and mike going out, sarah?"
"no not anymore, we are just comforable friends"
being comfortable friends just seems to work better for john and myself, we are a little more grounded to other parts of life now.