Honestly, just pack something with a USB port, and no descriptor. No labels, no nothing. Hell, make it out of a little hobby box container and put a port on it. Done.

Some dumb ass will plug it in to see what it is.

Remember, police have a maximum intelligence limit for hiring, or so its rumored, and if you've dealt with many cops, well.... seems pretty fair.

Intelligent people ask questions. Fascism doesn't like people asking questions.