>> Do it to me and I'll flash you back when you get
In Germany truck drivers help each other this way on overtaking.
German autobahns are quite narrow and trucks may only drive up to 100km/h
while limousines usually drive from 120km/h up to their maximum speed if
allowed. So one truck overtaking another one blocks the autobahn temporaly.
The truck being overtaken therefore signals with a short flash, that the
overtaking truck is now far enough ahead to return into the right track to
release the left track of the autobahn. Usually 10 or 20 meters. Especially
weak trucks apologize this way for their climbing hills at 60-80km/h.
After this maneuver the overtaking truck shakes hands with his handle for
the turn signals to say "thankyou": This blinks once right and left.
Greetings from Frankfurt
Torsten Kaiser