1. Euphemism for (and misspelling of) "chatbox". Doubly appropriate, since lots of people who use chatboxes can't spell, and also contribute ideas which amount to turds.
Combination of "empty nest syndrome" and "catbox," describing the empty feeling when, for whatever reason, you no longer have a cat (and the accompanying turds in the catbox) to take care of.
Fluffy left for college. I'm suffering from empty catbox syndrome.