Actualy some of us feel that naruto is actualy a girl who's had the power of the 9tails alterd to make her appear as a boy so she'd be trained better and be more dominate but that naruto's true form is a girl. This explains how the sexy jinsu comes so easily.:)
...Sexy Jinsu comes easily to him because he's a nerd. Ask any nerd alive. We think about women. Naruto is good at Sexy whatever because he wants some fucking ass!