This type of striped design is used in my team spirit hat pattern.
In my team spirit hat, this stitch is worked in a rectangle, which is then used to form a tube.
If you want to make a tube using this stitch, the instructions are slightly different.
To work a sample like this one, you'll need two colors of yarn: color A and color B. I used wool yarn in purple and yellow. You can use any colors or fibers you like.
Using color A, start with a foundation chain of any number of stitches.
Row 1: Continue working in color A. Single crochet in the second chain from your hook, and in every chain stitch across the row. When you get to the last stitch in the row, insert your hook as usual and draw up a loop. Then switch to color B by drawing through a loop of color B to complete the stitch. When you do this, make sure to leave a long tail of color B for weaving in later.
Evaluate whether you'd like to carry your yarn up the sides of your work. If so, you can just drop the unused yarn and pick it up again later when you need it next.
Row 2: Work a turning chain and turn the work. Using color B, work one single crochet stitch in the back loop of each single crochet, all the way across the row.
Row 3: Continue using color B. Work a turning chain and turn. Work the entire row in single crochet, again working only in the back loops. At the end of the row, change back to color A.
Row 4: Work a turning chain and turn. Work another row of single crochet in color A, continuing to work only in the back loops.
Row 5: Work a turning chain and turn. Work another row of single crochet in color A, continuing to work only in the back loops.
When you get to the last single crochet stitch in the row, switch back to color B.
Continue alternating between the two colors.
Final Row:When your project is the desired size, end with a single row of Color A.
Then you can stitch the first row to the last row using A HREF="http://crochet.about.com/od/learntocrochet/tp/how-to-slip-stitch-in-crochet.htm">slip stitch as shown above. In my sample photo, I'm crocheting the slip stitch in white so you can see it, but when you do this you'd want to use color A, so the join won't be obvious.