You won’t find kiddies selling it by the curbside. But ”hard” lemonades — which contain up to 5.9 percent alcohol — are making a big citrusy splash. One analyst predicts these bottled brands, bearing such good-ol’-boy names as Mike, Jed, Del, ”Doc” Otis, and One-Eyed Jack, will sell 12 million cases this year. And celebs are slurpin’ up the hooch too: Keanu Reeves reportedly chugged it at a Dogstar show, and ‘N Sync’s newly legal Lance Bass stocked his Madison Square Garden dressing room with a case. Why the popularity? ”The mix of lemonade and alcohol is such a simple and familiar concept,” explains mike’s hard lemonade’s VP of Marketing Russell Barnett. Sure, just like mom didn’t used to make.