This was unintended and just happened. Good teaching experience for all of us as we were ready to learn more.
I worked six days a week summers and had only Sundays off. One hot August Sunday I invited a friend, Pam, to go swimming at a local rock quarry that was surrounded by woods. We had dated a few times and she was fun to be with, but no one I had serious plans for.
She was 16 and from a different state. The family had a summer place in my town and the mother and kids spent most of the summer there.
When I got there she asked if her older sister, Jan, could join us to cool off too. We piled into my old heap and drove the several miles to the quarry. Pam had a cute, very slim figure, probably A cup while her sister was 17 and a D cup kind of overweight nice kid.
Once there, they changed on one side of the car and I on the other. They both wore two piece swim suits which was a bit unusual back then. I think their mother was French and encouraged it in some way. We then walked a half mile in on an old, unpassable road to find no one else there. It was popular in the early summer but not later for some reason. I think people preferred the beaches at the lakes.
There was a 6' wide ledge at the side of the quarry just covered by water and we used it as a place to dive in or to sit while swimming.
They had jumped in and I dove in, spending quite a while playing around and cooling off. I went to the side and sat on the ledge, followed by Jan, who proceeded to pull herself up. As she did so her top fell down and her tits were exposed. She was a bit slow in realizing it and I had a wonderful view of her tits. She then whooped and fell back into the water. She tried to tie it up again but wasn't successful. She swam over and turned around asking me to tie it up for her. I felt her tit as I reached over to get the front and complied in tying it. Her sister heard the commotion and swam over to find out what was going on. Jan was flushed with embarrassment and I said it was no big deal but that the view was big. She said you must have enjoyed it, pointing to the evident tent in my trunks and said you're big too. They were both stunned at seeing it, which I didn't try to hide. I explained that guys get that way when they see those sort of sights. Pam said it probably wouldn't happen with hers and I was able to honestly reply that of course it would, size wasn't the issue but the view was what mattered to me. With that she untied her top and let it drop. We all started to laugh and someone said we ought to skinny dip. That sounded like a grand idea to me, so I hopped into the water, pulled off the trunks and within seconds felt that exhilaration of being nude swimming with two girls. They threw their suits up beside mine and I went under water to see what the view was like. It was blurred and disappointing. They did the same, too. Feeling impish, at some point I said watch and floated on my back with my toes and head showing and slowly let the tip of my cock just barely rise above the surface. They thought it was a riot to see the erection sticking up. At this point things moved fast as one of them asked to touch it. I said of course and pulled myself up onto the ledge. They were in the water kind of inspecting and touching when Pam asked how it shoots white stuff. Her sister snickered and said its called sperm and said you had to shake it. So I offered to show them if they would sit beside me and I could see them too, without the swim suits. It was a fun time having them take turns jerking me off and having them watch me jerk off for them. I was so excited that it happened too quickly.
I shot quite a few feet as it came out and they thought it was a lot of fun to see. Quite a memory over the years.
A week later we three went to the drive-in movies and it was a cool, end of summer misty night. So we got into the back seat with me between them and did it again with them removing their undies along the way for me to inspect them. It was interesting they both had the same exciting musky smell, what a turn on. Guys adore that smell.
That was it. Their father passed away during the following winter, the mother sold the cottage and they didn't return. But it was a fun learning experience for all of us. Until then I had no idea girls could have an orgasm without intercourse. What fun.