When my husband was small, he visited his grandparents very often. When he was 5, he was staying with them for an extended period and his grandfather was making lunch. DH saw his grandpa take a can out of the cabinet, then use the can opener to open it.
DH could smell fish, and he told his grandpa, "Can't eat cat food, grandpa, gotta eat meat!"
DH is in his 40's and that is still a favorite reminder his aunts and uncles love to tease him with.