[vvrmyetr] Random sentence generator for passphrase initialisms

Consider a password scheme of using the initial letters of each word in a memorable sentence.  Create a random sentence generator to generate such memorable sentences, whose initial letters have a good distribution over all strings of a given length.

A better, or more fun, way to do it might be to start with a uniformly random (say) 8 character string, and have the user create a sentence with those initials.  Furthermore, the user is permitted to add additional words (likely articles, prepositions, and other "form" words) to help construct a memorable sentence.  This lengthens the initialism passphrase and is no longer uniform over the longer word length, but still has the 8 random characters worth of entropy that it started with.

Start with "vvrmyetr". Voracious Velociraptors Require More Yams to Eat Than Red meat.  End with "vvrmytetrm".

Perhaps avoid letters that are unusual initials, e.g., x.  Would using the second letters be easier? Or, add Th Wh Sh Ch. (The above example no longer works because Than is TH; we instead need a T word that is not Th.)

Perhaps a game about who can create memorable sentences, and development and dissemination of wisdom on how.