Jerry Seinfeld’s long-awaited return to stand-up saw him tackle Twitter and Facebook at the same time Mark Zuckerberg’s site was boasting it has 1 billion users. The former NBC star told the Beacon Theater crowd Thursday: “Facebook is one of the great trash receptacles of human time. Of course when you are young and dumb you think people are great . . . When you are 50, your first thought is the fewer people you have anything to do with, the better. Then there’s lawyers and Mace and cease-and-desist letters.” On the topic of Twitter, the comic espoused, “Why say a lot of things to everybody when I can say absolutely nothing to anybody? . . . Twitter of course was based on a bird, the logo is a bird and the bird was first to tweet. Why should they be the only ones dropping a series of small daily turds on the world — we can do it, too! A turd in 140 characters or less.” Asked during an audience Q&A about his favorite “Seinfeld” episodes, he admitted, “Like you, I can’t really at this point remember which stories go with which episodes. But . . . I remember when George [Jason Alexander] accidentally poisoned his fiancée, when he hit the golf ball into the blow hole of the whale and the time I got to steal the rye bread from the old lady.” We’re told Jerry didn’t have an after-party following the show, but instead went home six blocks away to be with his family.