One night, a long time ago, way before my youngest two were even born, we had pancakes or french toast for dinner. Probably french toast, because M makes really good french toast. Anyway, my much-loved grown-up daughter (who wasn't grown up yet) asked us to "Pass the ketchup, please. I mean the syrup."
We had a chuckle over her mistake, but sadly, the damage was done. You see, my toddler-aged son heard her mistake and from that moment on he has gotten the two confused. And he has passed that confusion down to every single child I have had since. It usually isn't too bad, unless we have both french toast and hash browns. This, mixed with F's love for ketchup over syrup, makes a funny meal. She asks for a bowl of ketchup to eat, we say, "Don't you mean syrup? And no. You can't have a whole bowl of syrup." But really. She wants a whole bowl of ketchup. And eats it with a spoon. YUCK!
The other two words my kids mix up are raw and rotten. That leads to some funny conversations, especially when we talk about our milk!