n.

The result of clear "traveler" beer bottles post drinking on long car trips. Especially evident around large signs displaying distances to locations (or "score boards") and can range in sizes from near full bottles to absolute dust depending on variables such as local speed limits, build quality of road furniture and skill level / level of intoxication of bottle ejector.

Also -

Road Emeralds - green bottles
Road Rubys - brown bottles

when you've done something so cringe you can't stop replaying it in your head and it stops you from getting on with your every day life