My room mate and I have been getting pimples on our upper backs recently, and we have come to the conclusion that it must be for wearing tank tops while lifting in our campus gym. Everyone sweats all over the benches and it gets on our backs. So I started wearing t-shirts again, and the frequency of pimples has decreased but I still get a few occasionally. Any advice here? Am I wrong about how I'm getting the pimples? Do any of you get these? How can I get rid of them?