Kid can't even talk yet, and I'm worried about him watching his language.
He's got this phonetic refrigerator magnet kit -- one magnet for each letter, plus an electronic box, also magnetic, that plays a little song about each letter's sound when you plug the right magnet into it. (Erika's posted before about Casey's favorite letter.)
This weekend he got a little private rhythm game going, holding a letter in each hand, plugging one into the box, then the other, just swapping the letters back and forth. The letters he chose: F and U. So thanks to Casey, our refrigerator spent two minutes singing, "F says fuh! ... U says you! ... F says fuh! ... U says you!" And so forth. Someday that'll warrant a grounding, but at this age, I'll give him a pass.
