Several of my patterns ask you to "cut the yarn and thread it on to a blunt ended needle, passing through the sts on the needle and then fasten off". This is used where you want to gather the stitches together, instead of carrying out the usual bind off/cast off.
This is how you do this:
1. Cut the yarn the suggested length and thread the end onto a large eyed blunt ended sewing needle.
2. With the right side of the work facing you pass the needle through each stitch on the knitting needle starting with the stitch closest to the tip of the knitting needle.
3. Once the yarn has been passed through each stitch, remove the knitting needle from all the stitches.
4. You should now have the head (or other body part) with each of the stitches "secured" by the thread passing through each of them. Pull the end of the yarn and this will gather together the stitches. You need this to be fairly tight as this will be the top part of the head that you'll see.
5. Then fasten off by sewing a small stitch on the edge of the last row to stop the yarn from slipping. Strictly speaking this step is academic as you will use this thread to close the seam
which will stop the last row from unravelling but if you are not sewing up straight away, sewing this small stitch will stop the whole lot being unravelled in your bag!