Guitar Center is launching a new coupon code campaign today – for Friday the 13th.Â The coupon takes 13% off of a single item over $130.00 (maximum discount is $500). The offer starts today (5/13) and is active until 5/16. At checkout simply use the following coupon code: FRIDAY13! <= I’m not sure if the ‘!’ is suppose to be there, but it almost appears that you do. If you use the code, can someone confirm this for me and I’ll update the post. Click here for full details on the coupon.