I recently moved across the country, driving from Arizona to Connecticut with a dog in my back seat and my wife and the cats in the next car. At some point in the drive, somewhere along the I-40 between a Taco Bell in Amarillo, Texas, and a hotel room with no air conditioning in Clinton, Oklahome, a semi-truck passed another semi in front of me. Truck A had succeeded in passing truck B, with me in tow, but the driver was having trouble telling if he was far enough ahead to change back into the right lane. His turn signal was flickering, but he wasn’t confident enough to move. After a while, trucker B turned his lights off for a couple of seconds, signaling the all-clear. After changing lanes without incident, trucker A turned on his emergency lights for a moment as a sign of gratitude.

You don’t always get that much cooperation on the road, maybe a high beam or two, but the whole thing seemed like a norm for the truckers. Struggling turn signal, “may I?” Lights out, “all good.” Lane change. Flash a “thank you.” It reminded me of one of the weirder things I saw in Uganda.

Uganda’s roads rarely have lanes, but colonialism still says drive on the left. Whether you’re on the newly paved (and wonderful!) highways or on a pothole-riddled street, cars will be driving with turn signals constantly flickering left and right. It took me a while to get it, and I still might be missing something, but the conversation that I tried to decipher came to this: if there were cars behind you and you were going too slow, it was your job to let them know if they could pass you. A right turn signal would indicate that there was oncoming traffic, and that they should wait a little longer. A left turn signal was the go-ahead to pass.

It was a fascinating thing to see if you had no idea what was going on, because the truck in front of you would constantly be signaling in every direction while going straight on a highway across the country. I don’t know how it arose or if it occurs in other countries, but I’d love to know. If you know more about this, or about other communicating-while-driving customs, I’d love to hear about it.