Hi, @okshakes.
Let me help share some information about how we can set up a payroll deduction for your contractor.
You can create an account in QBO for Other Current Asset and set up a Payroll Deduction Item from Net Pay if you are paying your contractor through your payroll. You can set this as wage garnishment then instead of linking this to liability, you link it to that Other Current Asset account as an advance repayment. It reduces their compensation but does not affect any other tax computations. You can refer to this related post: https://community.intuit.com/questions/1733460-how-to-deduct-employee-personal-expenses-from-payroll.
If the contractor will be paying through money, you can treat the contractor as a customer and create a sales receipt. But if it will be deducted to the contractor's payable, you'll just have to add a negative amount on the Bill/Expense for the T-shirt item.
This will get you on the right track. Please let me know if you have additional questions. I'll be here to help however I can.
