"Moral Decay" and such

"Mom, what is moral decay?" my son with autism asked out of the blue one day. We were in the kitchen at our house. I was washing some pots at the sink and he was sitting at the dining table attempting to reconfigure his transformer car. I bit my lips trying to hide the smile that threatened to break out and potentially hurt his feelings. I came around and sat down with him trying to explain what I thought "moral decay" means. He did not pause nor did he look up from his intense occupation with his toy but I think he was chewing on the information even as I fumbled through the conversation as best as I could. I used the word "fumbled" for a reason. He is still asking me about the definition of "moral decay" few times a day. I still continue to fumble.
Another phrase he recently wanted to know about was "crude humour". I left it up to his dad to explain that one. He is after all his child, too. I also thought my husband might just be better at explaining that one away.
So, this is where we are at with our 7 year old son. He hears things on TV or his computer games and youtube videos of the sinking of the Titanic and repeats them in ordinary conversations. He sounds formal. He uses big words. Kids his age would never be heard using those words. But, who cares. He wants to talk to others about things he is interested in. His peers either look at him oddly or brushes him off. I've seen one of them in a profoundly animated conversation with him in the hallway of the school. Their faces were full of expressions, their gestures sweeping as far as their little arms could reach and once in a while one of them made a whooping sound. I stood there thinking and appreciating the scene. As the bell rang, the other boy said goodbye and as he ran past me I said to him. "Looks like you were having a great time there. What were you two talking about?" The friend shrugged and replied, "I don't know what he was talking about." Then he went on his way. When my son finally managed to drag himself to me, I asked him what he was talking to his friend about and he said, "Roblox game" (it's a computer game that he's been obsessing about it for a while. The game is not really known to his peers, especially when he introduces the subject without preamble. He knows about it so why shouldn't others know about it, right? Theory of mind yada yada stuff experts say about children on the spectrum) I said "Uh, huh."
At least, this time it was not about the Titanic, the iceberg, the crow's nest, the engine room or about driving to Pittsburgh, USA, to go on a cruise ship!
Work in progress, as always!