My toothbrush. The bag of books I saved all year to read on vacation.
Oh, and power steering fluid. I developed a sudden need for this while I was gone. It’s been so long since I had a car that broke down all the time that at first, I didn’t recognize the sound. All I knew was that it was late at night, I was driving home on a dark, rural road, and my car was making horrible loud moaning and thumping noises. (I really hate that.) Fortunately, it was no big deal — but it made for a tense ride.