wool - n - gather

Slip 1 knitwise, knit 2 together, pass slip stitch over knit 2 together. This is a double left-leaning decrease. It's a fairly tidy decrease that is easy to make.

Insert the right hand needle into a stitch as if to knit and slip it off the left hand needle onto the right hand needle, insert the right hand needle into the second stitch and the first stitch knitwise, wrap the yarn around the right hand needle and pull it through both stitches sliding them off the left hand needle with the new stitch on the right hand needle, insert the left hand needle into the slipped stitch and bring it over the knit 2 together stitch and off the right hand needle.