Going without undershorts, said of a male, so called because his balls hang free and unencumbered. A similar expression is "going commando," which can be used of either a male or female without underwear, but is more often used of a male.
"A lot of guys like to freeball in the summer, but I prefer jockey shorts, to give my balls a little support, since otherwise they hang too low in the heat. I do freeball if I'm anticipating a sexual encounter, however!"
