"The stupid tax", an additional (and generally avoidable) taxation upon your regular habits.
In gaming terms the "stupid tax" is generally a reference to getting scammed or key-logged by a trojan virus. Often resulting in a lost of several game items or your game account.
StupidTax Anything you end up paying for something dumb you did…
I loaned a so-called friend of mine $100 bucks, I knew he didn’t like to pay his bills so why did I think he was going to pay me back? Now I’m paying StupidTax.