I lived in a small dorm in New York for a year. One night, Matt, the kid next door, came into my room (he was 15 and very tall!). He said he couldn't sleep so we talked for a while. He was sitting on the floor and I said 'hey why don't you sit on my bed?' (I was sitting on one side of the bed) so he sat after a while of nonsense talking, I started to get really tired but I could not lay down because my bed wasn't long enough, I guess Matt noticed and said I could lay on his lap.
So I put my pillow on his lap and when I put my head down my hand was still under the pillow, so I felt his rock-hard cock right on my hand. He noticed the 'stiffness' of my pillow and in response; he put his hands on my chest. I looked up at him, he smiled, and opened his legs, I pushed my pillow out of the way and pushed my hand into his boxers and started pumping his dick. He moaned and thrust his hips up and down, threw his head back, one last moan and cum shot out of his hard penis.
Shortly afterwards he returned the favor, we had several more re-encounters afterwards, but let's leave those for other stories.