The puff stitch is one of my favorite stitches that gives the yarn a subtle puff in the piece. I've used it to make the lettuce on this hamburger dress and some amazing scarves.
Step Two: Insert hook into next stitch, yarn over and pull through a loop. (3 loops on hook).
Step Three: Yarn over. (4 loops on hook).
Step Four: Insert hook into the same stitch, yarn over and pull through a loop. (5 loops on hook).
Step Six: Insert hook into the same stitch, yarn over and pull through a loop. (7 loops on hook).
Step 8: Chain 1 to secure the puff stitch.
The puff stitch is in the middle, in between double crochets, giving the piece a slightly puffed look.