Same thing with my brother and our cousins. We explored by dry humping, my brother humping with all of us. Our oldest cousin might have knew why it was feeling so good because I recall her "getting enough" with serious and tired tone and then getting off of him, but all the other of us just did it because it felt good. We didn't even had orgasms back then. Later years when we were teens and plays with cousins were left behind, my brother and me continued and then we used our moms brand new back massager too and then we also had orgasms. At first when I had orgasms, I felt awkward. Then when my brother also began to have his orgasms and spraying his cum, having orgasm right in front of him, or when dry humping with him didn't feel bad anymore.

In middle school mutual masterbation and spooning in our underpants was normal play for us at sleepovers. There's the submissive inside spooners that enjoyed pleasing the more aggressive outside spooners.
I was the first cute inside spoon to feel the sharp stab of a tighty-whitie aside penetration. Lol, I think I was pushing back as hard as he was forward because it felt good. I wasn't expecting a penetration, just heavy grinding by two cute and curious boys. When his penis penetrated I let out a soprano like shrill and panted like a puppy as he wiggled it all in.