An expression for a dead giveaway when playing a role-playing game. This is from the all too common experience of a Game Master who won't provide any detail for any of the rooms the characters encounter, but then provides a highly detailed description for one particular room or object, such as a mosaic the party discovers. This usually indicates something special about the object or room. Maybe it'll be a trap or maybe the key to the whole adventure. Either way, the players will focus on that object.

This is such a common occurrence that Game Masters have been known to emphasize the wrong object in a room, causing in the party to focus on that thing so much that they miss the otherwise obvious.