Mix two middle-aged children, their parents, and alcohol for a delightfully potent comedy! A well-to-do family becomes shaken and stirred when their middle-aged son announces he’s written a play about them. Filled with Martini-dry wit, “Cocktail” is  an emotionally satisfying comedy about a family on the rocks starring Ellen Crawford and Mike Genovese, seated,  (from NBC’s E.R.), last seen at The Public Theatre in On Golden Pond, and Kyle Knauf and Beth Hylton, as John, the playwright,  and Nina, his sister. The show is playing Oct. 17-26. For tickets call 782-3200 or visit www.thepublictheatre.org