Moon-Circuit Hacker is played or ninjutsu'd successfully the first time it enters the battlefield.
BUT...
On the following turn if it deals damage to the opponent, you are asked if you would like draw a card. If you decline, no draw or discard should take place. If you say "yes" it draws and forces discard like normal, however if you say "no", it is supposed to not draw or discard. If you select "no" it does not draw a card, and yet it still forces you to discard when you should not have to.