On One-Track Minds
The most prominent male stereotype out there has to be "men are only after one thing." This one's tricky: sure there are guys out there that are only after sex. We've all had run-ins with sketchballs who clearly have bad intentions, but my impression after living among males for twenty-some years is that this group is the vast minority. Scientific studies and filler material on 20/20 have shown that men think about sex more often than women, but for the most of us it's certainly not the only thing on our minds (see above entry "On Listening"). Watch any sitcom for an hour or two and you'll indefinitely come across a scene where a guy fantasizes about a woman while that bow-chicka-bow-wow porno music plays. It's ridiculous. No one ever hears that music during sexy fantasies.
Sometimes thoughts about sex will come out of nowhere. Without any visual, aural, or olfactory trigger, I'll find myself thinking sexy thoughts. These only last a moment or two and are always accompanied by a feeling of "what the hell was that?" For as much brain power as I dedicate to the subject, I really don't get any satisfaction out of it. I believe the poet Keats (though it could have been Marvin Gaye) said it best: "Ain't nothing like the real thing, baby."