So we were watching the penguins at the Academy of Sciences in San Francisco. All of a sudden these two in the back started going at it, in front of everybody. A bunch of children got hasty explanations of animal mating by their parents. After several minutes the birds finished up, and then stood side by side. The male slowly puffed and puffed himself up bigger and bigger, then threw his flipper over the female's back, like, "Yeah, I hit that, what are you going to do?"