Highway joke/riddle signs

Cruising down the highway, all of us have seen those huge LED signs displaying blurbs on the hoards of traffic stretching for miles ahead thanks to accidents and construction. In fact just seeing these signs can make your day just that much worse...

Instead of seeing these depressing messages of just how grim the situation is, why not replace them with quality jokes bound to take that edge off? For fairness sake, these signs could be located conveniently between exits as to make sure no commuter misses the punch line. the type of traffic may also determine content, jokes may be fine for slow but moving traffic, however in times of heavy traffic, the signs may flip into "riddle mode" displaying stimulating brain-teasers, giving the commuter plenty to think about (besides firing the "behind the headlights" stinger missiles up the exhaust of the nearest car) for the next mile or so of bumper to bumper traffic. This idea would also work wonders in subduing impatient passengers (such as children) on long cross country trips.