I have a few "what if" moments myself, around my mid to late teen years, 6th/7th form high school chums and other people I heard stories about, other guys that gave bjs and that sort of thing. I knew I was gay from around 15 or so. Had some crushes, one boy was hanging out with a lot, we used to get up to mischief as teens do (nothing sexual as such, although he did get changed around me a couple of times, which was hot. Loved seeing him in those boxers. He teased me once, just playfully, grabbing his crotch and dancing around like a stripper....hah. I should have taken it farther.) He was really into WWE and wrestling so we'd wrestle from time to time. He pinned me down one time and, basically lying on top of me, I swear he got a hard on. Someone else at school told me he sucked other guys off, I wished for a while after high school that I did something about it, I was kind of a late bloomer though, didn't really finish going through puberty until my early 20s, so I was keen but nervous about my lack of pubic/body hair and penis size etc. Silly lad, eh?... If I knew then what I do now....
There was another kid that I didn't socialise much with in school but he knew some of my female friends, and he was fairly friendly with me when I did speak to him, he was extremely camp/effeminate and twinky, and I did have a wee crush, but being naive and inexperienced, didn't try anything and couldn't really tell if he was interested in me, I bet he was and would have loved me to get rough with him... heh. Again, I was a nervous teen, and the odd run in I had with him was relegated to chit chat. Not even a kiss..... ugh. Haha. Ideas of what we could do together became a fantasy shortly after, also.
I started cruising parks and toilets in my early 20s, started with saunas and bookstores a few years after.
Not too many regrets, but I wish someone had told me about douching, good quality lubes and butt plugs earlier.