I'd ask your mom, to ask him for you, at this rate. It's her household to run. If he's not going to be an active participant, as an adult, living at home, then it's up to both your parents, actually, to have a talk with him...

Not sure, there really is a diplomatic way, to ask your brother, to help you out, putting away the groceries. You aren't mutually sharing living quarters, you are both under the same roof, by virtue of sharing the same parents.

At least, you will be equipped, to handle, living on your own, when that time comes.