I was showing my erect nipples

One more experience from a recent summer month. Someone on this website convinced me to tell this story, so here it is:

As so often, three friends of mine and I went to one of the large quarry ponds in our region. I was wearing a white tshirt and light blue shorts, and my bikini underneath a we cycled there. It was pretty hot and humid day, and for whatever reason, we had chosen one of the ponds that was quite some distance from the city. Once arrived, we dropped our cycles and want straight for the water to cool off. What a welcome relief. We continued to have a lot of fund throughout the day as usual; being in the water, sunbathing, drinking some booze...
Towards the late afternoon when we just came out of the water again, we saw dark clouds of a summer storm starting form and the wind picking up. We decided to quickly pack our belongings and head home. Unfortunately, I didn't bring underwear and I didn't want to wear my still wet bikini underneath my clothes. So I decided, once again, to go without underwear. I managed to get out of my wet bikini top and bottoms and into my tshirt and shorts without anyone of the others seeing anything. And compared to last time I had learned to not wear a skirt but shorts (well in truth, it was just a lucky coincidence).
Once everyone was ready, we cycled straight back to the city. Unfortunately, the rain started after only one third of the distance. And it was pouring down relentlessly. Very quickly everyone we soaking wet and we were looking for a shelter. Luckily at the half-way point, there was a place to get out of the rain. Calling it a coffee shop would give the wrong impression; it was more like a room with a single table and two benches, staffed by the local farmer. But he was not here at the moment, so we all just huddled in and made ourselves comfortable on the benches, glad to be out of the rain. One of my friends quickly suggested to take a photo of the whole situation. So the two other guys sit to the left and right of me as he took a picture from the other side of the table with us all smiling nicely at the camera.
Only once he showed the picture, did I realize that not only was my tshirt wet, it was soaked and clinging very visibly to the outline of my breasts, showing everything, my arolas and nipples nicely and erect from the cold. I was furious at them, not telling me and tricking me into the photo, but also at me for not realizing it. I wanted to leave, but it was still pouring outside and there was no other place to sit in that small cofee room. So I stayed put, but crossed my arms angrily, which only squeezed my breasts more as I could read from the widening eyes of my so-called friend sitting opposite me.
The other guys to my sides tried to calm me down, lowering my arms and saying that it was completely natural, nothing to be upset about. I started to relax again, but only until I noticed that the friend to my right had not just lowered my arm, but replaced it with his hand cupping my breast instead. As I didn't immediately brush him off, he squeezed a bit to test his luck, and I felt my nipples get more erect as I noticibly breathed out. I finally shock his hand off my breast, but here I was, stuck until the storm was over and "proudly" presenting my breasts and erect nipples in front of my male friends through a soaking wet, semi-transparent tshirt.

And I think this is as far as I take this story today.

This was the wet tshirt that I was wearing:
https://www.imagebam.com/view/GA8IFA