DEAR ABBY: Last week I was out with my family of 13 for dinner. My sister-in-law was sitting relaxed in her chair, stretching her back and extending her stomach. The waiter came over and, trying to make small talk, asked her, “What’s the occasion? Are you pregnant?” My sister-in-law isn’t pregnant, but her posture may have suggested it. Well, my brother, her husband, went off on the man, calling h…