Read this strip at gocomics.com.
There was a recent comment about Violet's family likely being wealthier than Charlie Brown's, which seems likely. This strip is evidence that Shermy's might be too -- or at least he might be more of a train freak.
Shermy's train set is obviously set up in his family's living room, or some sort of sitting room. How long must that have taken to set up, and how many times would his family have stepped on it by accident?
