I remember as a kid that we would say something was catercorner if it was diagonally opposite of something. We must have gotten that from mom and dad, because that doesn’t seem like a word that you learn in school. I think now I probably say cattycorner (apparently a southern thing), but I’ve heard people say kittycorner as well (maybe a black thing). It turns out all of these can be used.
Catercorner is the original version of the word and is apparently not based on cats, but on the French word for four, “quatre,” an old form of which was “cater.” This link says that the word is an example of folk etymology, which happens when people change a word to make it more like words they are familiar with. Other examples are “piggyback,” based on “pick-a-back” and “wheelbarrow” from “wheel bearwe.”