Dogs can be a person's best friend; they can also be their funniest friend! 

This Dog Loves To Play Dead!
This dog is the master at playing dead when being shot with pretend gun!
How Did Steven Teach Stella To Do This?
Unfortunately it’s not entirely clear. People have asked under some of his videos, but all he can offer is that the head flinging is her own flair…so she’s a clever girl eh?!
Steven has said that he tries to build anticipation, leaving a pause before saying bang. Then when Stella would sometimes offer a head fling he would try to treat and praise her more than normal, trying to encourage her to do it more. Well, it certainly worked :-)