This bad looking boy just isn't so bad as it looks. This is a garter
snake -- a California Red Garter Snake. With those markings it almost
looks like someone crocheted it!
While garter snakes were long thought to be non-venomous, it turns out that they do emit a mild neurotoxin While it is not lethal to humans, it can produce a reaction of mild discomfort in humans.
Image via I F***ing Love Science
Additional information via Wikipedia