Can I Use My Vote To Prove My Sister Wrong?

So, my sister is interning for McCain's campaign (along with many, many other people, I'm sure), and she is convinced that if McCain wins, she will get a job in the White House. Now, I am pretty sure that is absolutely false. So, is it wrong if a little part of me (not the part of me that will vote) wants McCain to win just so I can say "I told you so"?