Early in the morning when we woke, Big brother showed me that Little brother's pillow case had came off from his pillow.
Big Brother: Don't worry mummy! I will help you!
(And then he actually put the pillow back into the pillow case!)
Feeling very touched by his sensibility, i said to him "Thank you sooooo much! You are so sweet! It's so sweet of you to help me!"
Big brother: Huh? What's sweet?
Me: Sweet means it's very nice of you!
Big Brother: But i am not sweet! I cannot be sweet you know?
Me: Baby it's just another meaning, when i said you are so sweet, it means you did something very nice for me, it made me feel so happy
Big Brother: But but but! I don't want to be sweet!