6. Use trucker code to say "thank you"
When someone holds the door for you, you say “thank you.” Thank a trucker by turning your hazards on for a second or two, or by signaling left-right-left-right. You’ll stand out as one of the rare four wheelers who gets it. Courtesy: pass it on.
7. Use trucker code to say "go ahead"
You’re basically a tiny, two-dimensional object in a trucker’s mirror. So for them to know whether the back of their trailer is clear of your front bumper takes experience and really good guesswork. Signal to the driver that he or she has enough room to get in front of you by 1) turning your headlights on and off if it’s during the day, or 2) turning them off and back on if it’s at night. (Yes it's illegal to drive with your lights off at night, but there’s not a cop on the road that doesn’t know exactly what you’re doing -- and that it’s a good thing.)
Either way, never flash your brights as a signal, especially at night, since the glare can blind drivers if they’re looking in their mirror.