When I moved to university a few years ago, I ended up finding a room house sharing with two other girls, and we instantly hit it off. Before we knew it we were all best buddies and would talk about absolutely everything, including sex of course – we were cool with each other bringing guys home, and would talk frankly about whatever was on our minds in that regard.
This story actually starts months ago – we were all going through a sexless spell for some reason, and during a girls night in and after a lot of drinking one of us piped up something along the lines of "I just want a guy who I can call up to come and eat me out anytime". We all agreed that this sounded great, and we ended up joking that maybe we should share one guy and have him on-call to go down on us, before talking about where we'd find one and so on while laughing our asses off. Somehow, that conversation became a running joke, and we'd often refer back to it as a joke, or as a general way of admitting that we were feeling horny at that point in time.