I made these for a friend. I think I need to make some for me. They were very simple, I c/o 60 stitches on size 2 needles. I knit in a k3 p2 rib for three inches. At that point I ran a piece of yarn through the last 20 stitches to save for later and continued around the remaining 40 for five rows. I like to bind off (loosely!) alternating knit and purl (that makes the last row on top instead of the side, and I like that look better). Next I put the 20 st from before back on needles and knit them for five rows using the same binding off technique.
Make some. Be happy. Flip-flops can now be worn in April & May when we're not sure if it's going to be warm and sunny or cold(ish) and snowy.