Accounts Receivable (A/R) Discounted

You tie-dye T-shirts with political messages on them, and you sell them on weekends at the park. You don't take cash; you trust the park-goers who buy from you, for some reason. They agree to pay you when you send them a bill...within 30 days of purchase. And they can take 10% off the price if they actually do pay you within 30 days and agree to wear those shirts at political rallies. The sales from those T-shirts are an account receivable to you, subject to the above conditions being met.