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".
A dance move that has you flopping around your sweaty balls. Works better if you and another guy try and make your balls touch while flopping them around.
Joe: Hey Michael!! Let’s do the Sweaty Ballsack Shimmy!!
"You going to the dessert this weekend"
"Nah, Man...I checked the weather report and it's gonna be hotter than a sweaty ballsack in Dubai"
"Damn, Bro...THAT hot"
"Yeah, Man...THAT hot"