From Oblivion, 2004.
What I like about the quote is that it comes as close to anything I've ever read that explains why I often feel so misunderstood (which is essentially, all the time). I find that trying to express even very simple things to be very difficult... this quote captures a lot of that feeling.
I do plan on reading Infinite Jest a 3rd time. I'm not super keen on the theme involving the rolling wheelchair assassins, but I love the rest of it.
(And even more fun would be to OCR the book (Infinite Jest) and then run an analysis of the language used)
And while we're at it, here's a link to 15 great David Foster Wallace quotes.