It's just a (funny) way to give your chickens more room to run around without letting them destroy the garden or lawn (urban farmer types). In our case we had a former goat pen which was not being used so we wanted to give the chickens access to it and we may a 30' long tunnel between their...
The City Art Farm logo is a goat with a chicken standing on his back. So we did the logo and had the goat and chicken standing over the Seattle cityscape.