Yeah; "being a trendy youth." It's intrinsically tied to metropolitan bicycle messengers, who drew it from track racing, although in my case I drew most of the motivation from an aging Bostonian bicycle man (
Sheldon Brown). See also:
Fixed Gear Gallery
The button makes the set of lights above the tunnel flash, which is somehow supposed to suggest that drivers slow down (55mph to 30mph). Mostly it seemed to make them honk even more. (What the shit to honking in tunnels.)