Does anyone know what a scallop is?

Since you mentioned scrap booking, I'll ume they mean a scalloped edge. It's a decorative border, resembling the outer edge of a scallop shell when viewed edge-on. There are special scissors with the shape available wherever you get your scrap booking supplies. Take a look here: http://www.scrapbookerstemptation.com/index.php?_a=viewProd&productId=443 for an example.