Earlier quoted context omitted.
Hmm, what if we keep some encrypted porn in the shell OS? "Yep, there is hidden data. Do I really need to decrypt my special folder because I really wouldn't like to? OK then, the password is.." Disclaimer: this is all being speculative, of course. I'm not suggesting to lie to or misdirect a border guard in a real-life situation.
Good work, you've just confessed to a crime. Importing pornography into the US is illegal. https://motherboard.vice.com/en_us/article/us-customs-is-req...
For the sake of this discussion, replace porn with old passport scans and unimportant banking documents, for example.