My roommate ended up stumbling into my room and landed on my bed. He started getting handsy, and I immediately knew where this was going. He told me to relax, and I was pretty horny anyways. He ended up giving me a blowjob, and it was completely mind-blowing. We ended up doing things the rest of the time I lived with him. I eventually reciprocated, but we never did anything aside from oral or masturbation.
'Looking back, I have no regrets about any of it. It was a good experience, and I wouldn't change anything.' I don't think it defined my sexuality, because I still identify as straight.