42 Knock Out

I want to create an Itunes account but have reached a dilemma. I have a gift card and prefer to use it instead of a credit card but I might need it later. First of all, is it possible to create an account without entering a credit card, and doing it later? I prefer to have it charged to my gift card first. Also, if it is compulsory to attach a credit card, which one do purchases get charged to first?

Even though, this is probably the dumbest possible thing to do but if you punch your own face intentionally, can you knock yourself out? I ask this because your body/brain is anticipating the punch and your body/brain will know the magnitude of the punch. Because the majority of KO punches are unanticipated and the victim will not know the magnitude/strength of the punch therefore unconsciousness.