I have recovered enough from the horror of being forced to travel in close proximity with Nibbler (who gets sick and vomits) and Oliver (who has intestinal problems) to update our Weird Word entries. Mom and dad have argued about this stupid phrase several times, and each of their insistence that they are correct has driven me to resolve it.
The word is "catty corner", or maybe "kitty corner", or perhaps even "caddy corner", depending on whose definition you use.
Mom favors "kitty corner", which I don't like. Why would you want us in the corner?
Dad favors "caddy corner", which is really no better because it is just stupid.
Acceptable, but still stupid
What they are both trying to say is "two things diagonally across from each other". While that is the lengthiest way to get your point across at least you don't sound like an oaf while doing it.