My brother needs a number 2 pencil for the crucial test, but I'm going to give him a number 4 pencil.
Why would you not give him the right materials?
I'm doing it to show him that the world isn't fair.
Your brother needs the correct pencil or else he may fail the test. You really should not intentionally make him fail the test since it could have a large impact on his life. You should do the right thing and give him the correct kind of pencil.
Nah. I want to see him fail.
That seems a little harsh to do to your brother. You should not try to sabotage him right before his test, you should just give him the correct pencil.