Concentration is a music album by artists Machines of Loving Grace which was released in 1993. The song "Butterfly Wings" achieved moderate success and appeared on the soundtrack to the film Punisher: War Zone, as well as the TV Series Due South.
After the track has finished, the song trigger for happiness is followed largely by silence with the exception of a "don't fool yourself" sample being played every several minutes. The tracks remaining run time was intended to "fool" the listener into thinking a hidden track would play at some point, but this never occurs.