All sounds CC-by-sa Julien Jorge, produced with the following samples.

boing:
CC-by gezortenplotz http://www.freesound.org/people/gezortenplotz/sounds/20131/

bwow:
CC-by NoiseCollector http://www.freesound.org/people/NoiseCollector/sounds/24293/

hit-2:
CC-0 simon.rue http://www.freesound.org/people/simon.rue/sounds/49961/

