My brother does that. I have to do the shopping with him a lot and he always wants to fill the cart with junk food, and I start to get onto him because, you know, first off, it's junk, second, I can't eat it, and third, it's not like we can afford to buy everyone their favorite snacks right now, so why don't we buy nice, cheap, healthy snacks as opposed to expensive junk food that some people refuse to allow into their body!?
Then we get into a whining contest in the middle of the store over it and, being the little sister and the one with the car keys who can refuse to let him and his junk into the car, I win.
He does come home with soda every once in a while, but I can't drink the stuff anyway so I don't care. After being off it for who knows how long it all tastes like dirt to me.