You woke up, getting a weird taste in your mouth, as you noticed that your arms, torso, and head were still completely normal. What wasn't normal though, was how you got up, and when you got an odd taste in your mouth. Not only that, but you began to get a feeling that you couldn't feel your own legs at all.
It's almost as if you didn't have legs, but the question was how were you still moving. You go to the bathroom to see what has happened, and while you begin to move some what. You were still topless, but as you open your mouth, you found that your two front teeth have become fangs laced with venom, while your tongue has been changed to look like that of a snakes long enough to lick. You then look down, to find that your two legs have been replaced with a long green scaly snake tail.