If you've bought a new garment with this X on it here's what you need to know. This is known as a Tailor's Tack and it's a large, loose temporary stitch to hold a pleat closed during shipment. If the pleat on a jacket or a kick pleat on a skirt gets folded open during storage and shipping it can get heat-set and may not lay down properly, ever. By adding this quick stitch, it holds it in place nicely. Then, you can just take scissors and snip the thread and it should pull out quickly. If it gets stuck there may be the original knot still in there - just find the knot and pull out. Viola' - you're ready to wear!