Heng Chou... smelly smelly

I forgot when Ethan learns how to say chou chou... I guess it must be that time when he sat on the potty and keep forcing the air out of the potty (by lifting his buttocks up.. then down). Por por will tell him "heng chou lar!"... and I remembered he picked up the hand gestures from me, when I signed to him the other day.

He'll say chou chou everytime he sees the rubbish collection truck.

Yesterday on the car trip home, Ethan sat on my lap and he started saying "mummy chou chou" I'm surprised, but I asked him "mummy chou chou ah?", then he looked at me and continued "dong dong chou chou.. por por heng chou.. daddy chou chou... edan chou chou..." with the his finger gestures... haha.. wondered what makes him said that.