My nephew loved to identify and learn about animals, and would say "fucks" when he meant "fox". My dad, who was notoriously anti-swearing, would have him on his lap showing him an animal picture book and would repeatedly go back to asking him to identify the fox in the picture. Then my dad would cackle like there's no tomorrow, followed by my nephew who began laughing because his grandpa was laughing, but not knowing why. Me, my sister and her childhood friend were watching from the sidelines also ROTFLing, not so much about my nephew but because it was so out of character for my dad to be so jovial about swearing. Had I said "fuck" around him when I was a kid, it would be no TV for a week.