McDonalds is right over the road from C.C Puerto Rico Shopping Centre. I went for a sneaky chcocolate Sunday the other day and on the takeaway window I noticed a sticker.
If you are claiming "paro" you will get 10 percent discount from McDonalds, bear in mind you will have to show them the bit of paper you have that prooves you claim paro, but I though it was a nice tip to share. It also applies to other McDonalds on the island, it has a list of which ones are offering the discount.