The old adage says that a guy thinks about sex every 7 seconds. A recent study shifts that estimate:
Among a college-age population of 163 mixed-gender respondents, the median frequency of sexual thoughts for men was just 19. Women, meanwhile, weren’t far behind at a median of 10 naughty thoughts per day. … [But] the researchers found that men think about biological urges in general (hunger, tiredness, and, indeed, lust) a little more often than women do.
However, [study author Dr. Terri Fisher] notes that this could be due to gender-specific socialization in our society that discourages women from expressing their physical desires openly, as opposed to a true sex-based distinction.
Stephanie Pappas provides more detail:
There was a broad range in the number of sex thoughts, from several participants who recorded one thought a day, to a male participant who recorded 388 thoughts in a day. Factoring in the participant's sleep time, his 388 thoughts broke down to having a sexual thought every 158 seconds, Fisher said, still far fewer than the "every seven seconds" legend would suggest.
The Dish 