My frd staying with her sis and bro in HDB... one day HDB guy
came and asked for owner, then she said her sis and bro not in,
then the guy asked for my frd's IC.
HDB ppl can ask for IC one ar? then we can reject or not? only
police in uniform can ask for it, right?
If they asked you for IC outside your area of residence, you ALWAYS
have the rights to say NO and plus [email protected]#$$%^%^^&* to them, unleash your dogs
on them and slam your door at their face.
I would've politely asked them to wait outside my house
while I go take my IC, then of course I will naturally close my
door as politely as I could and go back to my bed to sleep.
He can always shout outside my door, but I'm quite sure my
dogs won't be so quiet and friendly to him. 
If they need to ASK, it means they do not have any RIGHTS at
all.