We're not sure how well this works, but you have the give the City of San Francisco a 'A' for effort.

This sign is located at the bottom of Lombard Street on Russian Hill between Hyde and Leavenworth Streets stating that noise is strictly forbidden (and to think, we've been doing it the hard way all these years when all we needed to give our clients was a street sign).

Incidentally, Lombard Street is also known as the 'crookedest street in the world' for within this particular one-block section, there are eight sharp turns (or switchbacks) to temper the streets 51% grade (a real hazard for modern cars let alone the Ford Model T when the road was built in 1922).