So, what's a knitter to do?
Despite the time and knitting already spent, I ripped the needles out and stuffed the half sock into my bag. When we arrived at our destination, I tossed the sock and remaining yarn into the nearest trash bin. Life is just too short to knit with crappy yarn.
On the way home, I cast on some wristers with some beautiful scraps i had in my bag. It was a much more satisfying drive.
And now here is a nice photo of giant yams at market.