Amen to MK's answer. This very much depends upon where you are, the merchant involved, the overall condition of the garment itself, and whether or not you have anything like a long term relationship with the merchant.
If the garment is easily place for re-selling, then at the very least, you should get a store credit.
I was once at Lowe's and was about to open a bundle of landscaping timbers because what was free was wet and warped. (That's like you, Boss; all wet and warped!- Bubba). A salesman came up and told me that it was not allowed. I smiled at him and told him that I felt his request was most foolish and asked to speak to a manager. He cut the bundle open immediately-- never contacting the manager. And the obvious moral is this- keep you cool and ask for a higher authority if the one speaking to you does not help.