Do you want to be my best friend ?

Now-a-days Sanjiv ask this question quite often and for almost everything.....
'Do u want to be my best friend ?, then listen to me.'
'Do u want to be my best friend ?, then give me one more chocolate . '

'Do u want to be my best friend ?, then charge my bike (the bike is fully charged though)....'
Sometime, he adds on 'Do you want me to be happy or not'...

Now, I have to make him understand that being best friend doesn't mean that one should do things blindly....
Now my reply is also pretty much same, 'Yes, I love to be your best friend but it doesn't mean I have to say yes to you. Being best friend means doing the right thing. So sorry, I can't do this because .....'
I really want him to understand what best friend means so that he chooses the right friends as he grows up.