The spell "Guards and Wards" has the following effect:
Confusion: Where there are choices in direction- such as a corridor intersection or side passage- a minor confusion-type effect functions so as to make it 50% probable that intruders believe they are going in the opposite direction from the one they actually chose. This is a mind-affecting effect. Saving Throw: none. Spell Resistance: yes.
How would you go about describing this to the players - and or running it in this day of drawn out maps and such - I'm curious because I was trying to figure out what to do with this mechanic - or if it would be a neat 'one time thing' but grow totally obnoxious to play out at the table.
Include some 4-way intersections and allow the map to make them believe they are going the right way. Some 3-way intersections could be drawn as 4-ways. You could also draw the map wrong if it serves your purpose. In the case of G&W I would let the map portray their perception, rather than the actual layout of the dungeon. You could also not use a map.