Toss a coin - in your case a ten-sided coin - and trust that all the other folk like you out there will do the same.
Yep. That was what I thought of, too. That, and how it would've saved Arnold Rimmer from smudging his crib notes in Red Dwarf.
A coworker of mine in an open plan office did once set up a mirror. Another coworker crawled under a desk to avoid the field of view and said "Boo!" to great effect.
As for the poll topic itself, I tend to know and trust the people around me. Is it worse to be a possible easy target like Johnny ("They got him sitting with his back to the door, now he won't be my fast gun any more" - Billy Joel, Say Goodbye to Hollywood), or to get wound up for certain?
Those who can, do; those who can't, write. Those who can't write work for the Bell Labs Record.