Mine will hiss at any movement outside his cage at all, and yesterday was greatly angered at the sight of an alarm clock. But like I said, they 'mock strike' without opening their mouths. All bluff. It would be cool to see one play dead, but I don't want to scare mine that much, if I even could. They look and feel almost exactly like a rattlesnake, they have characteristics of certain cobras (Aspidelaps in particular), but you can still pick them up. Pretty cool.