mullet lawn
A lawn which is well cared for on the front side of the house, but in disarray on the back, much like a mullet - "business in the front, party in the back".
The Hendersons have such a mullet lawn. It's just like their marriage - they're always putting on their best face for the neighborhood, but deep down, they have issues...
lawn mullet
The front lawn is cut short and manicured, while the lawn in the backyard is left long and uncut.
Compare your front and backyard lawn cutting to a mullet hairstyle where the hair in the front and back of the head are shorn differently: short in the front, long in the back. A lawn mullet has short grass in the front of the house and long, unkempt grass in the backyard.