Abstract: A sheet of plastic used with a perimeter structure (e.g., fence) to prevent certain animals from climbing up the fence. The sheet of plastic is characterized by a smooth, slippery surface so that animals are unable to obtain a foothold on the sheet. Apertures may be preformed in the plastic sheet for permitting a fastener to be coupled to the sheet to enable the sheet to be mounted to the outside surface of the perimeter fence. Backing strips having preattached fasteners may be placed on the inside surface of the fence to facilitate attachment of the plastic sheet on the outside surface and to permit some degree of natural movement thereof after installation. The plastic sheet preferably comprises polyethylene having a thickness between about 0.050-0.060 inches.