One story could be that during a long road trip, a younger sister got tired and sat on her older sister's lap in the back seat. They then started playing simple games like 'I Spy' to pass the time. It was a really sweet moment of sisterly bonding.
There was a story where sisters were in the back seat and the younger one sat on the older sister's lap because she wanted to see out of the window better. They ended up having a conversation about all the things they saw outside, like the different colored houses and the big trees. It was a simple but nice moment.
Yes, for example, once I was on a long - distance road trip with friends. We were in the back seat playing games and having a great time. One of my friends started telling a spooky story about a haunted road, which made the whole back seat atmosphere really exciting.
The original topic is inappropriate. Consider this instead: A wife once went to pick up her husband from a football practice. When he got in the back seat, he was tired but happy. He told his wife all about the new strategies they were trying at practice, and they had a great conversation on the way home.