Kakashi, Naruto, and Sasuke are sitting together and talking. Cannot remember how it got brought up but somehow they say that Kakashi is a perv or slut and he says something like "What makes you think they were all women?" in an attempt to shock Sasuke and Naruto (mostly Naruto). It backfires because Naruto takes him seriously and is genuinely curious. And very shy about it. And Sasuke offers to show Naruto how it works. At which point Kakashi was thinking something like "Now I just wish I was flexible enough to kick my own ass". As far as I can remember the fic was either a oneshot or very short. I realize it is not much to go on but any help would be appreciated.