The 'Caught short' rule, rolled at moments of high tension when a player hasn't indicated that they have taken proper precautions. e.g.,
GM: Okay everyone. Zoarth stands before you. His wings spread over you and block the sun. He lift's his snout to the sky and his roar leaves your ears ringing. He then lowers his smoking nostrils and looks at you with disdain - as if to say "ready when you are." (He grins at the players) Okay guys - this is finally it.Your chance for revenge. All of you will have to be at your best to defeat him.
Garry: ALRIGHT!!! I stare up at the Dragon and call Drakesbane to Aly'stro's hand. Let's DO thi...
GM: Hang on Garry. I haven't finished. (smiling the Evil GM SMILE) Chris, I need you to make a bladder check please.
Rest of the group: ?!!?!
GM: Sorry, but he didn't indicate he that he took a chance at the clearing. That was 3 hours ago. And he ignored a free bladder warning when you were crossing the canyon. You know the rules.
Garry: (to Chris) I can't believe you didn't go before we left. For Pete's sake. What level are you?
Chris: 20! Shuttup! I was busy at the clearing. And who do you think held off the Stone Hags in the Canyon?
Steve: Bull! You weren't busy in the clearing! You were on the phone to your girlfriend when we all erased our bladder points. I knew I should have said something. Your uric acidity was already up to seven and you didn't say anything. Seven! Seriously, you should have just pissed on the Hags - you would have done more damage.
GM: (interrupting) Quiet, everyone! Chris, ROLL. Now! If you fail you need to take a 1d4 rounds to go. If you succeed, you won't need to roll again. Unless, of course, the Dragon uses a Fear attack, or casts Uncontrollable Hideous Laughter at you...