3. Something you yell out for no reason
Original meaning that seems to have been erased from existence: A small, spherical object used for sports
2. He didn't have the balls to jump out the helicopter.
3. Random guy 1: "BALLS!"
Random guy 2: "....The hell is wrong with you?"
2) When used in conjunction with "...on your...," it becomes an expression synonymous with "Fuck you"; IE "Fuck you" means "Go get yourself raped," thus as the only thing fathomably worse than rape is teabagging, crying "Balls on your day, week, life... etc." is a curse on one's life.
3) Synonmous with "bullshit"; Thus, "Calling balls" is insisting that something is false or counterfeit, ala' calling bullshit or shenanigans.
2) That guy just cut me off in traffic! Balls on his day!
3) Wait, she's dating YOU? I call balls.
Hobbs: "Man, that's balls on your chin..."