I'm not going to give my father a loan of 40k
Why don't you want to give your dad a loan?
I don't need him and so I'll just say no to the shit
It is difficult to say no to your parents when they need your help but it is understandable if you don't want to loan a huge amount of money. It will however make your relationship more difficult.
You are right. I'm going to say yes if he ask me for 5k and tell him to get lost for 40k.
It is good that you want to help him out a little and that you are being cautious. A large amount as a loan is dangerous and risky.