"The sexual fantasies of a boy can be very different to those of a girl and on average the boys' fantasies are more erotic. When you get sexually involved with a boy he will bring his fantasies along. Often he will talk about trying 'new things' and about his strange fantasies. Generally this is very normal (but if it annoys you, you need to tell him). You might be worried about his furtive glances at other girls but ask him what his fantasies are about. This way you will generate an amazing and valuable conversation that allows you more and more to establish an affectionate intimacy".
Michael Gurian.