When Humbert Humbert (the narrator and main character in VN's novel Lolita, 1955) visits Lolita (now married to Dick Schiller and big with child) in Coalmont, Lolita calls her husband "a lamb:"
She was, as I say, talking. It now came in a relaxed flow. He was the only man she had ever been crazy about. What about Dick? Oh, Dick was a lamb, they were quite happy together, but she meant something different. And I had never counted, of course?