I had a friend who was likewise somewhat slutty. Talking about sex, what we were into, recent fucks, things we didn’t like in bed, etc. was a big part of our friendship. She had been in an open, long-term relationship with a man. They had mutually agreed that it was acceptable to fuck others, and it appeared that their agreement was working out well for them.
I was chatting with her boyfriend when he said that she never allowed him to fuck her ass. I made the (mainly kidding) offer to him that if he ever genuinely wanted to take some girl’s ass, he should hmu and I’d do it because I knew their relationship was open.
A few weeks later, he texted me to see if I was free and if he could come over. I nodded in agreement, and approximately 30 minutes later we were both in my kitchen. After a brief period of small talk, he asked me if I was serious when I said earlier that I would let him fuck me.