"Be Careful!" at Carrefour

In my fourth-grade English class, I was teaching the phrases "Look Out!" and "Be Careful!" When the students saw the word "careful" they screamed out, "Carrefour, Carrefour!" They were delighted because they thought they knew the word on the paper. I told them (in Spanish), "No, Carrefour is a French word which means intersection. This word, careful, is an English word and means 'ten cuidado.'" They looked shocked and horrified as they challenged me, "Carrefour is a store." I told them, yes, Carrefour is a French-owned grocery/department store, but it's name means intersection and, no, careful and Carrefour are not the same thing.