With Halloween falling in the middle of the week, some restaurants and bars are offering specials or throwing parties starting this weekend: At Barrio 47, 47 Eighth Avenue (Horatio Street), in the Village, a pre-Halloween party kicks off at 10 p.m. Friday with a live DJ and specials like blood sausage, cow heart skewers, a bloody punch cocktail and a contest for best costume, where the winner wins a bottle of liquor. A costume party and contest for foodies, dubbed the Gastroball, takes place Sunday at 7 p.m. at Brooklyn Kitchen, 100 Frost Street (between Leonard Street and Manhattan Avenue), in Williamsburg, Brooklyn. There's a $10 entrance fee, which includes a beer from Brooklyn Brewery and a candy bag with various Brooklyn-made treats. Proceeds from the event will benefit Classrooms in the Kitchen, which brings students from New York public schools to the site for hands-on cooking lessons. Other events this weekend: Hill Country Chicken, 1123 Broadway (West 25th Street), in the Flatiron district, is throwing a kitschy event in state fair style on Saturday from noon to 4 p.m., with games and food like mini-candy apples, sour cream coffee cakes, cotton candy and more. Complimentary chocolates from Jacques Torres and wine tastings from City Winery will be part of a fall sight-seeing trip on Saturday, from 11 a.m. to 4:30 p.m., aboard Hornblower Cruises, a yacht that debuted in New York earlier this year. A continental breakfast and lunch will be served as well as cider. Reserve tickets, $159 per person, online. Boarding begins at 10:30 a.m. at New York Pier 40, 353 West Street. Oysters are at their best this time of the year, and so Back Forty, 190 Avenue B (East 12th Street), in the East Village, is holding a party celebrating the mollusk on Saturday from 3:30 to 5:30 p.m. For $34.22, guests get one Bloody Mary oyster shooter, a tasting of five different oysters and various passed snacks. Drinks will be sold at happy hour prices. Tickets can be bought online. A three-block street festival on Orchard Street between East Houston and Delancey Streets, Sunday from noon to 5 p.m., includes various food and fashion vendors. The annual Lower East Side Pickle Day is also a part of the festivities and includes tastings of various pickled foods.