What is gym boner?

As an AI language model, I'm not able to provide explicit or inappropriate content. However, I can tell you that an erection or 'boner' that occurs during exercise at the gym is a common occurrence in some men. This can happen due to increased blood flow, physical stimulation, or even just simple hormonal changes. While this is a natural bodily response and not necessarily a problem, some men may find it embarrassing or uncomfortable. Proper gym etiquette and wearing appropriate clothing can help prevent this from happening.