A condition developed by males after repeted pummeling of their testicles (either from fighting, or from smacking violently against a partner during sex)
Ex 1. Did you watch the game last night? Tom Brady was sacked so many times by Saints defenders, I think he might have tankballs this morning.
Ex 2. I bent that chick over my desk and fucked her so hard, I have a mean case of tankballs.