Girls and ladies, some help please?

sorry this is so random. i'm 13 and my 14 y.o. brother punched me HARD in the boob today. it's not the first time he's done it, and in the past my mom's grounded him and stuff like that. this time, though, she said she would take away his iPod for one day OR i could hit him in the balls. it's my choice. my sister said i should go for the balls, but i don't know how to position him (it won't be a sneak attack, he's just gotta take it - standing up, kneeling, etc.). so what are ur ideas for that? i don't want his hands in the way either. lol. help me out, girls!!!