Just like the evil TSA imaging systems, best thing to do is refuse to participate.
That's the point. If you refuse then they do a thorough search.
If you answer suspiciously, or refuse to answer, then you get the full search.
This is similar to how you can refuse body scans at the airport, but if you do then you get the full pat down search.
If you act very weirdly, like you are suggesting, then they will just make the decision to definitely search your bags.
Targeting people who act weirdly is kinda the entire point, though.