Brooklyn Bridge in New York is, apparently, a bit of a pain for cyclists. There’s a bike lane, but because the pedestrian path is right next to it separated by only a white line, everyone just sort of mills about oblivious to the division.
This rider clearly concluded that a bell wasn’t sufficient and instead employed a car horn.
They currently do two horns: the Loud Classic and the Loud Mini. They’re also working on the $349 Droid Horn with Traffic Droid.
If horns aren’t your thing, you could always sing “Bike lane! Don’t stand in the bike lane!” to the tune of the Star Wars theme, as Noam Osband did on New Year’s Day.