Well most guys are simple, not simple minded. (well some guys aren't.)
Most guys do think about perverted stuff here and there a lot. Sometimes they think about friends naked or in bed or etc.
Almost all guys masturbate, and sometimes even when you don't think they are doing so, like on the phone, or webcam, etc. They might try to hide it but I'm sure they are up to something.
Another thing is men think if girls wear a short skirt or tight revealing clothing, they think they could possible score with her. Men are more physical then females, so in a way they are a little bit more shallow.
- "OOoooooooMMMGG she's so CUTE when she does xxx" Girls will never know how soft and gushy I get when I see them interacting with anything at all. Be it the way she twirls her hair while she talks on the phone, the way she rubs her eyes when she's sleepy in class, the way she gets a little icing on her nose when she clumsily eats the cup cake... the only thing they see is the tough-guy deathmetal badass motherf***er who's too hardcore to talk much or smile.
- I love it when girls eat bananas. Sorry.
- You smell SO GOOD when you sit next to me. I want to smell more and just stick my head in your hair and f***ing smell everything.
I can't even think of secret guy things. We aren't as complex as you probably think. I'd be curious to see if people come up with real secrets guys have. Either its well known, or secrets are individual matters.
I'm a guy. I don't keep secrets. All you have to do is ask. I'll even tell girls I'm only dating them for sex. My conscience requires me to disclose everything. So I don't have to hear you bitch later.