Your future's a clam?

Please does any one know what the following meaning means:-

The worlds your oyster
But your futures a clam

thanks

I can help with the first part.

THE WORLD IS AN (ONE'S) OYSTER - "If you have a lot of money, you can have anything you want. The proverb first appears in Shakespeare's play 'The Merry Wives of Windsor' .'Falstaff: I will not lend thee a penny. Pistol: Why, then, the world's mine oyster, Which I with sword will open.' Act II, Scene II." From Random House Dictionary of Popular Proverbs and Sayings by Gregory Y. Titelman (Random House, New York, 1996).

A second reference says the phrase means: "All the pleasures and opportunities of life are open to someone because he is young, rich, handsome, successful, etc. Shakespeare invented or popularized this expression." From Encyclopedia of Word and Phrase Origins by Robert Hendrickson (Facts on File, New York, 1997).