As you already know, my kids make up words all the time, many of which are consistently used in consistent ways. One of these words is "The Boungy" (pronounced with a hard 'g'). It appears that a Boungy is some sort of imaginary rabbit. Our six year old, A, is the physical manifestation of this strange Platonic ideal.
Tonight when I went up to get them out of the bath I heard them making up words in Spanish for the first time. "The Boungy" is now "La Boungisia." Z followed this up with a longish Spanish sentence about La Boungisia that made her collapse into a helpless fit of laughter. I have no idea what she is talking about. I thought I had a couple more years of being able to figure it out.
Note to self: Take Spanish.