“A Good Old Fashioned Orgy” — There’s something old-fashioned about “A Good Old Fashioned Orgy,” but it’s not the orgy. Alex Gregory and Peter Huyck’s R-rated comedy feels more like a “Meatballs”-era summer romp, the kind we’re generally either too cynical for now or we’ve simply outgrown. It’s a party of a movie, for better or worse, with ambitions of generational resonance. Eric (Jason Sudeikis) would like to eradicate inhibition in a generation weaned on psychobabble, Blackberries and Radiohead. When his father decides to sell his East Hampton summer house, Eric and his early-30s friends (Tyler Labine, Martin Starr, Lake Bell, among them), decide to have a last-hurrah orgy. It sometimes looks like they had more fun making “Orgy” than we could possibly have watching it, but the good vibes are a big part of the movie’s appeal. (It should be noted, though, that “Orgy,” with its Hamptons setting and cargo shorts, is easily one of the whitest movies to come along in recent years.) The premise asks a lot of Sudeikis’ charm, but group sex, to say the least, is a tough cookie. When the time comes, the awkwardness of the participants pales in comparison to the awkwardness of the audience. R for pervasive strong sexual content, graphic nudity and language. 95 minutes. Two stars out of four. —Jake Coyle, AP Entertainment Writer