We made it (or rather him) to live in my little brother's playgroup, so it is rather enormous being around 240cm long, which works well with several kids playing in different places along the snake, but probably it should be scaled down for home use.
The idea came from my brother after I played Rikki-Tikki-Tavi with a rope and lots of kids in there.
The thing has to withhold the wildness 4-6 year-olds, so the yarn has to be as strong as possible.
We used yarn that is 50% cotton and 50% acrylic (Lana Gatto Summer), but acrylic should also work.
We used 50 grams (1 ball) of 2633, 2620, 2635,2629, 2675, 2630,2631 each - yellow, light blue, navy, black, ruby, purple and violet (I don't remember which is which), but any bright colours do. We also used 100 grams (2 balls)of green (2624), and lots of polyester toy stuffing.
Step 1: Head
I will use some common knitting abbreviations, they are easy to find in the internet, or here http://www.knittinghelp.com/videos/knitting-glossary(they even have a video of how to do it!)
CO 8 stitches and distribute them evenly between 4 dpns (double-pointed needles, the ones you knit socks with) and join the knitting to start the round.
Row 1: needle 1 - kfb, k1; needle 2-k1, kfb; needle 3 - kfb, k1; needle 4 - k1, kfb.
Row 2: k all.
Row 3: needle 1 - kfb, k2; needle 2-k2, kfb; needle 3 - kfb, k2; needle 4 - k2, kfb.
Row 4: k all.
Continue until you have 48 sts (12 on each needle).
Knit (k) 12 rows.
Row 1: needle 1 - k1, k2tog, k to end; needle 2 - k to last 3 sts, ssk, k1;
needle 3 - k1, k2tog, k to end; needle 4 - k to last 3 sts, ssk, k1.
Row 2: k all/
Row 3: as Row 1.
Continue until you have 40sts.
Sew on two buttons for eyes, or embroider them.
Step 2: Knit, knit, knit: the body.
In other words: knit, knit, knit... Until you run out of all the colourful yarn and have about a half of a ball of green left for the tail.
Keep stuffing in the process.
Step 3: Tail
Row 1: k1, k2tog, k to end on each needle.
Knit 6 rows without decreases.
Row 8: As Row 1.
Knit another 4 rows.
Row 13: As Row 1.
Knit further 3 rows.
Work until you have almost no yarn and 2 stitches on each needle left.
Thread your 8 stitches on the leftover of the yarn, tighten and hide the end.
Remember to stuff in the process.