Dan,
You need to understand what "original issue discount" means in this context. When somebody borrows $100 from the bank with at 15% OID, then the bank takes 15% off the top and only gives the borrower a net $85 in cash. The borrower then pays the stated interest rate, in this case 8%, on the full $100 and they will have to repay the $100 plus accrued interest.
Crunch the numbers and you will find that this deal has an effective interest annualized interest rate of approximately 21.3% because the company borrowed a net of $2,448 and will have to repay $3,232 in 18 months.