That's a way to take advantage of a truck's right-of-way.
I probably scream a bit. Get scared, and start getting p**sed at the driver.
If they were the ones in the way, they deserved it. My dad drives a Mack Semi-Truck for a trucking company. Some idiot came right next to his truck and started to merge at him on a bridge! He swerved over the the edge of the bridge and struck the side of the girder and took his mirror off, the person swerved back into their lane after noticing they were drifting, sped up to the front of the truck, and then cut my dad off!
His horn didn't do a thing!
Cheers,
Joshua