An "air horn" is a device that makes a loud noise by blowing air through it, often used to get people's attention or as a warning signal. Full definition
So, their dogs are yelled at, threatened, spanked, hit, blasted with air horns, had coin filled cans tossed at them, grabbed, chased, cornered, bullied, shot them with bb guns, poked, banished, pinned to the ground, or worse. (samthedogtrainer.com)
Helicopters hovered loudly overhead while hundreds of police officers erected barricades, and protesters rang cowbells, blew whistles, waved signs, and sounded air horns. (nymag.com)
Air Horn Spray Paint + Traffic Cone It acts as a really loud horn (so loud that Chuck has to cover one ear when he uses it) that, when used for an extended time against a crowd of zombies, will cause their heads to explode. (co-optimus.com)