I am not very good at being a guy. Now, don't get me wrong, I was lousy at being a girl. And I'm positive that there are plenty of guys who aren't that good at being guys. In the normally perceived way. I just don't know how to interact properly. Also, I'm socially awkward anyhow, so it's not just with guys. I just don't know how to act. What to say. So I tend to not say anything.
For the record, my boyfriend is great at being a guy.