From Kirkus Reviews ``My mom and dad were divorced,'' begins this refreshing variant on a familiar theme. Patricia and her brother stay with Dad and Gramma in the summer; when Dad seems to have forgotten Patricia's birthday, she takes it in stride, going along with him when he decides to stalk ``the Monster at Clay Pit Bottoms.'' After a picnic by moonlight, the kids are frightened out of their wits by an apparition, but it's just Dad--he fell into the pond and came out covered with bulrushes. Meanwhile, of course, Gramma has provided a birthday cake. Both the lively narrative and the energetic illustrations capture the thrill and humor of these shenanigans; Polacco's characters' flamboyant gestures, like mime, adroitly convey both their comically exaggerated reactions and their subtler feelings. (Picture book. 4-8) -- Copyright ©1991, Kirkus Associates, LP. All rights reserved.