lol sister not gonna happen..
Anyways you can tell him its bad for his health.
Chocolate can make you gain weight.
To much sugar, many calories acsessed.
To much can get you a belly ache.
I hope this helps :)
ways to try
1.) Eat fufilling meals that are richer in fiber and chocolate
2.) Find a healthy snack you like just as much
3.) stop carrying it in the house and skip buying it next time your at the store
4.) If all else fails replace milk chocolate with dark its a little heathier