Cycling with another adult on the back of a bike is not easy to do, but the people of the Netherlands certainly make it seem so. My guess is that it's a consequence of starting to cycle at a young age. Kids are fearless, creative and, you know, stupid. After years of practice they can cycle with no hands, while eating breakfast, or with their friend on the back. And they can also hitch a ride from their friend who is pedaling away without even holding on.
It's hard to do... Or not, see the guy behind the blond.