I got bit on my right ankle by a baby (guessing less than a couple of months old)
Southern Pacific Rattlesnake.
We had just moved into our house, literally days before, and I stepped outside around 7pm and the little sucker was on the doorstep and I stepped on it. Bit me before I even knew it was there. Just made my foot turn all black and pretty ugly, and gave me a very weird feeling muscle spasm in my face for about 2 hours - but it did get me out of work for a week while I sat on my butt with my foot elevated.
Since, in the 4 years since, we have had to remove a dozen or so from our front yard, from new born to very large adults [4'+], along with several Gophersnakes. We also had one California King that our cats caught, IN OUR LIVING ROOM, and decided that was our pet. just 8 inches long (about 1 month old), he is now almost 18".