Shh! Shhhh!

Finally recalled what I wanted to put down about 哥哥. This happened yesterday on the way home from school. This was the conversation after chatting with him on other stuff ...

妈妈 : So, have you been a good boy in class today?
哥哥 : Yes! I'm a good boy! Everyday!
妈妈 : Really?
哥哥 : Really! (Then he went on telling me what happened in his class today.)
妈妈 : Ah! Mrs Eunice is there. (His form teacher and 2 other teachers were walking in front of us, going for lunch.) I ask her if you are a good boy.
哥哥 : Shh! Shh! Shh! (Jumping about. I was caught by surprised.)
妈妈 : Why? Why? What happened? (Eyes open wide)
哥哥 : I .... a bit naughty lah. Only a little bit lah.
妈妈 : LOL

Ai yo! What to do with him huh?