Under the Sea.

Me (to a 3 year old girl): Want to look at some animal picture cards with me?  You could choose fish, mammals, reptiles...

Girl: How about mermaids?  Do you have any mermaids?

Me: No mermaids, but I have fish.  

Girl: Ok, fish.  They live with mermaids.

[She then proceeded to express her love for Disney's Ariel, explaining how much better Ariel is as a mermaid than as a human.]