Out of Ketchup

I woke up early to make breakfast for my brother.  I made bacon, eggs and hashbrown potatoes. We are out of ketchup. We were out last week. Paul knows this. He went to the store to pick up dish soap and ketchup but returned only with two 2 Litre bottles of coke.
"Where's the ketchup?" he asks. I indicate the tiny amount left in the bottle to which he scoffs.
He throws a five dollar bill in front of me and orders some ketchup, like a boss. I don't have a job so I know when I'm being spoken to like an employee. I can't remember the last time I felt so disrespected.

I don't mind paying for things, I paid for the bacon eggs and potatoes. I don't mind going out and getting things, I just don't want to be treated like a servant.

*Edit (Paul apologized and I feel better)