"You can have this ball back if you can prove it's yours."
"You just said you'd give it 'back' implying you already know it's mine."
"Nuh uh, that's not proof, because I'm holding it so clearly it I made it mine"
"Okay, then how do I prove it's mine?"
"I dunno. Not my problem"
"You don't really want to give me the ball back, do you."
"No, not really. No."
"Got it."