There’s an NSFW trailer out for “Sex Tape,” the Cameron Diaz-Jason Segel movie that filmed around Boston and Tufts University last fall. During filming, producers told locals that the movie would be called “Basic Math” (perhaps to appease business owners who allowed filming on their properties). But it appears that the “Sex Tape” title is back in use, which makes sense. The comedy is about a couple whose sex tape leaks for the world to see. It comes out this summer.