Occasionally I'll use an unusual word without even thinking about it, and then later realize that I've never uttered that word aloud before. Ever. It's a pretty weird feeling.
We play a game where you think of words you've never said before and try use them in a sentence. (So if you don't know roughly what it means, it doesn't count.) It's fun because you try unsuccessfully to search for words with the weakest indices before eventually finding profitable seams by thinking of the crazy stuff you've read.