This is a reprint of a pattern from The Running Yarn. She used Caron Simply Soft yarn [100% acrylic; worsted weight 4ply; 315 yd per 170g skein] on US #11/8.0 mm needles.
CO 40 st.
Row 1: k2, *(k2tog) x 3, (yo, k1) x 6, (k2tog) x 6, (yo, k1) x 6,(k2tog) x 3, (yo, k1) x 6, (k2tog) x 3, k2.
Row 2: k2, p to last two stitches, k2.
Repeat these two rows until the scarf is 6 feet long, or however long you want it.