My friend sent me this today. She lives in Boston. I think this encapsulates the Yankees/Red Sox rivalry about as well as anything:

This image tells many things:
- Yankee fans are everywhere, even in Boston.
- Yankee fans are rude (note how the Yankee fan covers his neighbor’s window with his signage).
- Red Sox fans have lousy grammatical skills (and potty mouths, to boot).
Go Yankees!