One of the coolest snakes around is the hognose snake. They are very docile and gentle, but have a whole host of fascinating behaviors, including this defensive bluff that makes them look like a little cobra.
Defensive behavior of Eastern hognose snake (Heterodon platyrhinos) (flattening head), Los Madrones Ranch in the Hill Country, Texas, USA.Canon 1Ds Mark III. I80 mm. 800 ISO. 1/40 sec. at f/8. EV + 1/3.