The space needed for a mans balls so he can be comfortable while sitting.
"Dude move your ass over i need some fucking ballspace"
"Charlie fucking move i need ballspace"
When two guys or more, mainly after drinking, are fighting over a topic where they both argue to make a winning point. They are fighting for ballspace because there is not enough space around all of them to prove whos got the biggest "balls" or ego to fit the room. this can go on for hours, untill one person gives up, the argument is broken up or one person passes out from drinking too much.
Ernie: "What are you talking about, if you think that a modified car can beat out a muscle car then youre crazy"
Bob: "WTV man modified cars can beat them anyday!"
.....an hour later...
Party goer: "what are they arguing about again?"
Party goer2: "Its all about ballspace man, cmon lets go get more beer."
Party goer: "F*cking ballspace"