Well explained by Nanila, but in case it helps, my version is "It's *Wooster*-shire, like Bertie!" =:o}

Also, to counter by far the most common (or do I just mean stereotypical?) American mis-pronunciation of British place names: When the suffix "-shire" appears as part of a place name, it *NEVER* rhymes with "tyre". That only happens if it's being used stand-alone, e.g. in a phrase such as "here in the shires", or Tolkien's "the shire". The RP pronunciation is "-sheer", but in casual speech most people will shorten the "ee" sound to an "i" or an "uh", depending on their regional accent.