Red flags are so last season

You should always clearly mark the end of a load sticking out of the
back of a truck or trailor. Most people use a red flag but at my job
we like to get a little more creative. A plastic soda or milk crate
and a red bucket. If someone does not see this creation it will be a "can't see the
forest for the trees" thing. They will be so busy trying to figure out
what the hell it is they'll run right into it :).