When I was in my late teens (18/19), I had a friend called Martin who I didn't realise was bi. I slept over at his house fairly often as we both lived with parents yet and were both still in college too. When I stayed, we had to share his bed as his parents were quite poor and there were no spare bedrooms. It had never occurred to me that it might lead to anything as we were just friends and staying over was the only way we could get more time together to chill.
One evening when I was sleeping over and his parents were out, he asked if he could practice a massage on me, I knew he was training to be a masseur at college, so it wasn't too weird. It became awkward however when it occurred to me that I needed to take some clothes off. Nevertheless, I said yes and awkwardly undressed down to my underwear, back in the 1970s we almost all wore Y-fronts, not even sure boxers were invented yet, and for anyone who used to wear them, you know there's not much chance of hiding your cock, size, nor state of arousal in those tight-fitting things. Martin could see I was a little embarrassed and so offered to strip down to his underwear too. Again, looking back, it was probably an intentional act, but in my 'innocence' I just thought he was trying to help me feel less embarrassed.
So having stripped down to underwear, I laid on my front on a thick blanket we had put on the floor of the bedroom. In this position, he massaged my back first and it felt really relaxing. Whenever he was at my head, he reached right down the length of my body to my waist with long hard pressure, it felt great, but I became aware of his cock sometimes grazing the back of my head. I wasn't entirely sure how I felt about it so I pushed it to the back of my mind as I was a straight guy....right, and so it wasn't sexual...right.
When he got onto my legs, he rubbed my thighs and sometimes got quite high with his thumbs, massaging my ass cheeks, and getting close to my chocolate starfish. If I didn't know he had a girlfriend, I would have begun to get concerned by now. One time he got very close, almost slid his thumb in, I put it down to accident, but it felt better than I had thought it might.
As a result of the close touching, I was getting aroused and I began to panic a little, I had started to get hard and realised that, at some point, he was going to want to massage my front. By the time he asked me to flip over, I was fully erect and totally embarrassed. I did however flip, desperately trying to ignore the fact that I had a hard on, but as he pretended to ignore it too, it eased my embarrassment somewhat.