I was 21 and living in a dorm. The semester was ending with just one exam left. My roommate and I were watching a sexy movie in our room. I got horny with my cock getting hard. As usual I started twisting my nipples with my fingers under the sheet. I could see that my roommate was playing with his cock as the sheet was moving.
I suddenly got up and slipped into my roommate's bed. I started sucking his hand, fingers and palm. He did the same to me. Suddenly and naturally, I started kissing his lips. We kept kissing for a while and our hands reached for each other's cocks. After sucking his fingers and lips, I started sucking his nipples while stroking his cock. After several minutes of kissing and stroking we both came together.
Almost thirty years later I still remember that and often masturbate imagining that incident. I am married now.