I just went out for a Subway sandwich and came back with 5 Max Richter CDs, a big Twix, a can of Condensed mushroom soup, and a beef poutine.
That was a costly and unexpected event.
A few years ago I went out to Costco for a frozen pizza and came back with a Learn German 10CD lesson set, a wheel of Black Bomber cheese, and a mystery novel set during the Great Fire of London.
Only several times a week. They say "Never go grocery shopping on an empty stomach", but even when I only go for a single item, hungry or not I almost always wind up buying more than I intended. And, too often, I forget to buy the item for which I originally went and I end up making another trip. Sometimes serendipity happens and it ends up for the better.