That's just their way of telling you that their litterbox is too small and/or filthy. Imagine how you would react if every time you needed to use the toilet that you were expected to walk around in your own waste in a tiny room so small that you could barely turn around? You'd find some way to protest the facilities too. The solution is to get a big, deep Rubbermaid tote, fill it about 4 inches deep with a low-dust clumping clay litter and cut cut an entrance for the cat about an inch above the litter line. That gives your cat plenty of room to walk around, depth for them to bury their waste, and high walls to contain any litter that's flung about as they dig. Scoop the box a minimum of once per day, and scrub the tub clean and fill it with fresh litter at least once per month. Don't use anything to try to mask the smell -- if it smells bad to you, it smells much worse to your cat given their keener sense of smell -- because if it smells, that's your clue that you need to increase your scooping/cleaning frequency. Also, make sure you have as many litter boxes as you do cats. Many cats prefer having their own box, plus sometimes more aggressive cats will purposely block more timid cats from being able to access a shared box as a way of asserting dominance. Yeah, that might seem like a lot of work, but again, think of your own toilet habits. Scooping the box is the cat equivalent to flushing the toilet. Cleaning the box and replacing the litter is like cleaning up urine from the bathroom floor and encrusted poop that's hung on through multplie flushings. Unless you're a foul bachelor(ette) frog, you do these things regularly, right? Well, your cat desires and deserves a clean "bathroom" just as much as you do. they are an asshole

FTFY