well,
Boys are simple. Usually we see things like frogs or snakes are very cool while girls think they are gross. Since guys think it is cool, they don't think that if the other person (most likely to a girl of his interest) like it or not. This is why boys act nasty and gross in girl's point of view.
This is because, boys don't think about their consequences(most of the time). Like in DC, young Shinichi broke in to the school while young Ran was saying "we should not do this," or "Let's go back" (or something like that...) this is because girls think about their consequences(This is just an example, it is actually true). This is probably why girls are more mature than boys, because they think about what will happen next. Boys are just... well, they want adventures, which is probably why they do stupid stuff.
But when it come to teenagers, both boys and girls begins to stop thinking about consequences. Turns out, most of them do. Me and my science teacher performed experiment in deans office, where the teachers would send the "bad kids". We tested them by asking "Do you know why you are here?" or "Why do you think you are here?".
Their responses were:
"I don't know."
"I didn't do any thing."
"It's the teacher's/someone else's fault."
"Because I said (most were profanity, sexual things, or some kind of annoyance like racist jokes). "
...and etc.
Those were the most popular responses.