Piranha 3-D looks like a lot of fun. It looks like blood, guts, boobies and action. And those attributes make Piranha 3-D exactly the kind of campy stage to showcase a gimmicky, has-been, still-not-impressive movie technique that is making a comeback, and hopefully a quick death, with 2010’s landing in all things 1980s. Yeah, I hate 3-D. So does Roger Ebert. And – gasp! – I even hate 3-D in Avatar. Suck on that, James Cameron. 3-D belongs in animated …