On the day of Febuary 17th, 2007 it was agreed by numerous males in the town of Westford, Massachusetts that due to the unusual temperature and amount of perspiration resulting from it that the day should be officaly deamed "Sweaty Ballsack Day".
The reason for this is that during this day many males complained of extremely high levels of sweat coming from their genitals, hence the term "Sweaty Ballsack Day".
Andrew: is it just me or is everyone getting sweaty balls??
Seth: DUDE ME TOO!! OMG this is like officialy Sweaty Ballsack Day.
Andrew: Hell yeah dude!