A mind-boggling habit!

Recently...Zach has taken to smacking his own head! While breastfeeding him, he seem to enjoy using his palm to smack his forehead! We suspect that he likes the sound it makes...cos he is now into smacking anything and everything in sight...our shoulders when we carry him, our thighs when we sit him on our laps, our faces when we carry him, his car seat when he is on it, his high chair when he is on it and the table when we its in sight. I wonder what goes on in his little mind!