When you get to the end of the sandwich, you think back on how you thought it was going to be, and are more than a bit let down. It looked like the perfect sandwich: great ingredients, bread toasted just so, and the right mix of mayo and/or mustard. But as you gorge down that last bit of crust, you realize that it wasn't as good as you imagined it would be; you'll still be hungry in a couple of hours, and probably you should have skipped the sauerkraut. It's hard, nonetheless, to finish those last crumbs, you want to savor it and make it last just a little while longer. Sure, there will be other sandwiches, but you had such high hopes for this one. There are other sandwiches in the deli; maybe next time you'll go for a sub.
