James Cameron didn’t like “Piranha 3D,” but enough ticket-buyers went to the toothy fish flick to inspire its high-minded producers to make a sequel. And it’s going to be interactive. Fans had so much fun seeing a Joe Francis-like character (played by Jerry O’Connell) have his manhood chomped off and fly across the theater, they’ll be asked to participate in an online contest to vote for the celebrity they’d like to see eaten, or killed by other methods, in the sequel. Suits at the Weinstein Company are expecting plenty of votes for the folks from “Jersey Shore” and the “Real Housewives.”