Let's just say you wanted to be an idiot and try to rob a convenience store, here is how you know that you have received a "FAIL."

In this case, the robber went into a Stop N Go in Ohio and tried to hold the place up. As you can see from the video below, the clerk have probably been robbed many times before, so this is old hat to him.

So the clerk tells the would-be robber that the cash register is empty, by saying "you must be tripping."

Being that this must be the first time the robber has had a level-headed clerk tell him that bad news, he stands there for a moment in shock and walks away.