When everyone is part of your threat model

found on eBaum's World

I'm not sure we would have much of a civilization if we couldn't trust each other most of the time, but if this is how much you trust people then I suppose you should act accordingly. 

You Can Trust Me shirt

Product Page

A great shirt for physical penetration testers, just not while they're on the job. 

I found this novel design while searching around for interesting security-related merchandise, and quite by accident I hovered over something and saw Graham Cluley's name pop up because it turns out this is his design. So thank Graham for this, and by thank him, I mean of course buy his shirt. 

Be careful who you trust

from here and here (image source)

Just as not all heroes wear capes, not all villains wear masks or twirl their mustaches. You can't tell just by looking if someone is trustworthy or not, you have to judge them by their deeds.