Unless you are trained to do undercover work, don't even think about lying. Chances are that this all goes swimmingly. But, if it does not and the CBP Officer starts asking simple questions and you provide evasive answers, it becomes easy to deny you entry, not because CBP suspects that you are visiting an illegal, but because you they think that your story is untrue and that you yourself will overstay.
If it comes to it, as shown above, it takes 3 quick questions to get to the nub of the issue.