Acronym coined on the LFGSS forum in London, usually a track bike that has never seen the track (i.e. tarck) and is used for sliding around Dalston or Shoreditch, showing off expensive, carbon, aerodynamic or otherwise rad components. All types of track bikes that may be slightly impractical but are nonetheless maximum rad to the power of epic awesome.
Foldable bikes and hybrids need not apply. In extreme circumstances (i.e. Landsharks) geared bikes may also be HHSB