(My brother runs a leisure club that has membership fees that feed a budget. They required a t-shirt design by the end of the week, when I had three other jobs on. My brother called me up and begged me to help him - he even offered me a few pounds to sweeten the deal. )
Brother: Tell me if you can do it or not. I have another guy who will if you don’t want to.
Myself: I’m really sorry, I’m busy now, and the clients I have sort of paying my rent. Not that I don’t mind the gesture (of offering me £10 to do it).
Brother: You are family, you should do it for free. I’m doing you a favour giving you money.
Myself: Sorry, I know, but I’m too busy. If the other guy wants to design it for £10, let him.
Brother: We are paying him £150, just thought I’d give you the opportunity first.
