OH, I get it.

So, when someone says, "My cup runneth over", it means they're trying to fit a C in an A. NOW it makes sense. So, like, if someone was tryin' to fit an X in a B, then that person's cup would be runnething overing all around the landsacpe, right? This is fortuitous, because not only does it explain one of life's mysteries to me, but it also explains why I flunked algebra all through school. You can put X into Y, but ya can't put Y into X. I wish Mr Smith was alive to read this thread. He would be so proud of me. Friggin' A.