If you haven’t yet been to the Park Slope outpost of the Grand Central Oyster Bar, which opened in December, you just might become a regular on Wednesday nights. That’s because the shellfish and mollusk purveyor has recently announced a weekly Cajun crawfish boil that is guaranteed to satiate all your dining-with-a-bib-on needs. The diminutive and delicious crustaceans are actually shipped live from Louisiana, prepared in beer and Old Bay, and served with the traditional potato and corn accompaniments. Best of all, they are presented as they should be, piled atop a table covered with newspaper. The meal is priced at $18.95 for one and $34.95 for two, which is actually a pretty good deal considering how far these little guys have to travel to be your dinner.