Bobble is a textured stitch which can be made with any type and number of crochet stitches. A pattern will usually specify the kind of bobble required. To create it you will make the number of stitches specified into the same spot, bringing them to a state of near completion by not doing the final yarn over and pull though two loops for all stitches. When you get to the final stitch, yarn over and pull through all loops on hook.