A ginger tabby alley-cat covered in curry and stuff. He is infested inside and out with every disease known to man. He meows like a bitch and growls at anything that moves. His tail always sticks up 90 degrees and shit flakes fly out his arse when he farts. His claws are like 9 inches long and make a bastard of a noise on hard ground.
He climbs in through the window when you're out, finds the whitest carpet/piece of furniture and wipes his arse all over it, leaving lovely brown streaks everywhere. On his way out he steals some food.
"Keep your doors and windows locked, for Skimbleshanks is on the loose! He will turdify any white furniture or carpet in your house!"