Trust me guys, I didn't come up with this.
I got this from a comic about guys playing pen-n-paper RPG games.

I was having the party run through a boxed campaign called “Dragon Mountain,” though I added in a few things to spice it up. One part called for the players to protect a town at the base of a town against a rampaging horde of kobolds and drive them back until reinforcements arrived. The thing is – these kobolds were smart. And the party didn’t know it.

So the fighter of the party took over the town’s defenses, and was doing pretty good. The kobolds had drawn battle lines all around the town, but had erected blinds to keep the party guessing to where the bulk of their army was. This is how the scenario went down –

Me – “You suddenly hear a gigantic, earth-shaking BOOM, followed shortly after by the sounds of walls collapsing. It seems like they’ve finally pushed back the defenders and breached the South Wall.

Fighter – “Rally the troops! Everyone to the South Wall! Everyone keep them from getting into the city! Hold the wall!”

Needless to say, the kobolds were in the process of swarming over the relatively undefended North Wall now and were in the city. During the fight, one of the rogues, a level 10, went toe to toe with one of the kobolds who was looting a shop.

Me – “Rogue, you see a small kobold eying you from about 20 feet away. He looks nervous, his eyes darting and looking for some of his friends, but none seem around. He waves a small jagged stick to keep you at bay, slowly backing off.”

Rogue – (Rolls and fails the check) “WTF?” (Yes, he said WTF. W-T-F. WTF is with that?)

Me – “Your world is suddenly vastly different. You see things from a lower perspective, and now want to eat a lot of grass.”