It means 'Be careful. The bridges will ice up before the roads do.' in idiotic english.
(
Mu Dinofiddler,
Thu 30 Jun 2011, 22:36,
archived)
Or
It's a message from the evil voice that lives inside Jeff Bridges' head, instructing him to take crystal meth before driving
(
Cassius Kray floats like a butterfly, stings like a trout,
Thu 30 Jun 2011, 22:46,
archived)