Whats a GOOD excuse for selling cupcakes?

You don't need to make up some story. You might sell more cupcakes now, but eventually someone will find out you lied to sell cupcakes and that'll be the end of that. If you need a reason to broadcast just say you're raising money to pay the bills. It doesn't really matter why you're selling them. If you have a good price and a good product, people will buy.