Before I stepped in her door that Sunday night, the only thing I knew about Grandmother Matthew was she bleached her hair and was in her second marriage to a man named Mickey and they were both truckdrivers."" But as punishment for shoplifting a pair of pantyhose, Christy, who's adopted, is being sent for a week with her ""bad grandmother""--who greets her with ""So you're Christy, the little thief. Come on in."" At first Gram ignores Christy, dragging her around to shop for a water heater or keep Gram's doctor's appointment or (more pointedly) see the inside of the jail. . . or else she watches her own programs on TV. (""Like your mother said, this isn't exactly the amusement park."") Then comes the thaw--swimming, scrabble, spaghetti dinner and even trying on Gram's first wedding dress--followed by a mutual emotional flood, when Gram assures Christy of her natural and her adoptive parents' love and. reveals that Christy's Mom was adopted too and that she herself was a foundling who grew up in an orphanage wishing to be adopted. Green comes crashing to the point here with all the subtlety of a pair of truckdrivers, but up till then Christy's bad grandmother has proved a refreshing change from the prevailing middle class model of nonconforming, hip old ladies.