The Letter S

Casey is now in kindergarden. Each week, they learn a new letter. This week, it's the letter S. He learns how to write it and what words begin with S. At home, the letter S comes up. He's asked what he is sitting on... "Sofa". He is asked what he is wearing.. "Socks... Shirt". Then he pulls up his shirt, exposing his underwear, points and says, "Sac". Oh Sh!t, apparently he knows his anatomy.. and the letter S.