More like MFF.
Once when I was younger my two female cousins and I were at my grandparents house. At the time we were pretty close. One cousin and I were both 13 the other was 14, I was pretty curious about the female body at that age. So we were just hanging out watching tv and talking. Our grandparents came in and told my cousins and I that we had to change to get ready for bed and that they were going to bed and we should say goodnight. So they went downstairs to their room to change. I changed and went downstairs to wait for them. I knocked on their door and asked how long it would be. They said not long and that I could come in if I wanted. Being the curious boy I was I opened the door and went it. There I saw my 14 year old cousin in a nice pair of purple panties with no bra and nice sized boobs for her age. I look to the other side of the bed and saw my 13 year old cousin trying to pull on her pink panties, she was struggling to put them on so I got a nice view of her little vagina.
My older cousin then asked if they could see mine now that I've seen them. So I figured that was fair and pulled down my shorts and boxers, and showed them my penis. They asked if they could touch it of course I said sure. So they started to touch me and I got harder and harder. Therefore I asked if they wanted to make me feel really good they said yes so I grabbed there hands and put them on my penis, and showed them how to jack a guy off. They both slowly rubbed me until I came. This happed a few more times but that's for a different story. Happy masturbating!