Question about BBQ oysters and how to prepare them?

You can buy them in the shell or in a container already shucked (shells removed) at any fish market. If the recipe calls for cooking out of the shell, just buy the container thats already cleaned. An oyster shucking knife is basically a short blade very dull two sided dagger. You can shuck them uncooked or roast them on the grill till the shell separates, they're pretty much done when the shell opens a little. To shuck (open) them, you hold the oyster tight, push the point of the knife into the back joint of the shell while twisting the blade gently back and forth. It can be dangerous if you've never done it. You can cut yourself on the knife or on the shell. If the recipe just calls for the "meat" of the oyster, just buy the shelled oysters. Its totally worth the extra cost to save the work. If they're cooked on the half shell, whoever helps you at the fish market can give you advice on how to shuck them.