Using size 17 needles and super-bulky yarn, cast on 50 stitches (either join in the round with a twist or work flat).
Work 34 rows in garter stitch.
Work the following rounds/rows as suggested:
R3, 14, 21, 32: *yo, k2tog
Bind off. Weave in ends. Sew seam with a twist if worked flat.