Did you have your dinner?

it can be both, like saying.. "Would you like to come to dinner" which can just mean a small just dinner type thing i guess and "would you like to come for dinner" i think would meanlike a party type...

You can do breakfast for dinner if you want but you won't look very good to others you git!

well if you don't you don't have to. What course usually comes after dinner is desert. You have sweets and stuff to freshen up your mouth after a spicy dinner!