Double yarn overs allow you to make larger, more dramatic holes in lace and can also be used for a simple buttonhole.
Working one is easy, you just wrap the yarn around the needle and additional time (you can even wrap it multiple times for even bigger holes),
but how do you work into 2 loops on the next row?
The crucial thing to know is that a double yarn over is really just a single loop of yarn that was wrapped twice to make it larger. You can slip one of the wraps off the end of the needle to see this larger single yarn over. You don’t need to open it up like this before working into it but either way you should treat the whole thing as one stitch — it will open up when you slip it off when your stitches are completed so you can work everything into the first wrap without worrying about the second.
Some patterns will have you knit into the front and back of the double yarn over and others will have you knit and purl. These have slightly different effects but it’s important never to work the same stitch consecutively — you need to put in that twist between your stitches to avoid everything opening up into another large single stitch.
They don’t have to look this evil!