Secret Masturbation

I was staying with my older cousin for a week in the summer at his parents cabin. We had to sleep in bunk beds. I was on the lower bunk. At night, I would always get a hardon and quietly masturbate as he lay sleeping above. I was jacking my hard cock as usual, careful not to make any noise or shake the bed, when I heard him quietly moaning. He was doing the same! That got me very excited. I paced myself to hold on until he stopped. We lay there in the dark, masturbating and the bed began to shake as he began to thrust his hips upward, straining to shoot his load. I matched his movements and ejaculated almost simultaneously. We drifted off to sleep without saying a word.