Photo-hog....actually... Photo-Squirrel

Melissa Brandts and her husband were exploring Lake Minnewanka in Banff National Park, Canada, when they stopped to take a timed photograph of themselves.
They had their camera set up on some rocks and were getting ready to take the picture when this curious little ground squirrel appeared, became intrigued with the sound of the focusing camera and popped right into the shot.

http://arbroath.blogspot.com/2009/08/look-what-popped-up-here.html