carrots, celery, morality, and other fibrous things

The following conversation occurred while The Smart one was helping The Temporary One with his 'how to be a good person' class. They were talking about what you should do if the cashier gives you an extra five dollars in change. Or something. 

Has it ever occurred to anyone else that 'moral fiber' is a weird phrase?

The Smart One (typing as he speaks): "I... would... probably...."

Me: "Keep the money. Cha-ching!"

TSO: "... Because I have no moral fiber."

Me: "Because you're like Wonder Bread, or something."

TSO: "And not a carrot."

Me: "I would probably keep the money because my moral fiber is more reminiscent of a cheeto than celery."

TSO (to The Temporary One): "Can I put that? Can we please say you're more like a cheeto than celery?"

The Temporary One: "Um.. No?"

TSO: "How about, 'I would return the money because my moral fiber is like celery?'" 

TTO: "No."

Me: "OH I KNOW! 'I would return the money because my moral fiber is more similar to the fiber content of those foods consumed by individuals of higher socioeconomic status than those of lower socioeconomic standing."

TSO/Me: "BAHAHAHAHAHAHAHA!"