Scientists from the Medical Research Center (Germany) have suggested that having sex regularly can make people smarter.  During foreplay and intercourse, large quantities of adrenalin and hydrocortisone are secreted.  These compounds stimiulate the grey matter of the brain, which in turn stimulates intellelctual activity, the team explains. 

Eighty-seven percent (87%) of adults in Greece engage in sex weekly, whereas 34% of adults in Japan report doing the same. ~ Global Sexual Wellbeing Survey 2006 by Durex Corp.