I was at the gym today as usual and I never talk to anybody. I keep my headphones on the whole time while I use many of the heavy machinery that most girls are afraid to use. Sometimes, I get stares or even glares by both men and women while using the weight machines, but I've never been talked to directly.
Today as I was working on the lateral pull down bar, a man at the adjacent machine approached me and started talking. I had my headphones on, so I heard "Be careful... [mumbled]". I thought he was telling me to be careful with the heavy weights. I said "What??" He spoke louder, "Be careful, you're getting too big!" and pointed at his biceps, laughing. I smiled and said "Oh, but I want that." He laughs and walks away.
I could imagine some women who might be offended by his comment, since its a stereotype that women should look a certain way and not have biceps too big. He seemed like a middle aged guy and I haven't seen him before, so I will forgive him. It might even be a compliment perhaps.