This happened when I was 18. My brother being 8 yrs older than I am at 26. We had the best mutual jo session I have ever had. We had to sleep together one night as I was living with my mom at the time and me and my bro were both helping her move into a new house. The new house was kinda barren, all we had done was assembled two beds so we could sleep and then continue the arduous task of moving the next morning. We had set up the beds, one for my mother in a room on the other side of the house and one for me and my brother.
When it was time to go to bed I got in just wearing underwear (it was July) and my brother got in completely nude. We had the covers on us but sitting up against the headboard. He started talking about sex and I got this huge hardon. We are big guys over 6 feet tall and needless to say have large penises. My bro has size 13 feet! He kinda turned to me and I felt his huge schlong on my leg. He said just feel that big thing and make it cum. I put my hand under the sheets and started playing with his hugeness.
His balls were miraculous and his cock was tremendous. He ripped my underwear off and started playing with me and jerking me off.
We got into a 69 position and jerked each other off really hard. We came all over our bodies, mouth and face and just fell asleep.