The waveforms named "NoiseBandXXX" define a non-harmonic sound band (even though it usually has a perceived pitch) centered on the sound's frequency.
Two sliders control the parameters of this waveform:
spread: the range (from 0 to +/-80Hz) over which the noise band is formed.
density: the density at which the noise band is filled. 0 means only one sine is generated, 1 means 240 parallel sine waves are generated across the spectrum.
The "CrazyNoise" examples are variations of this noise band. They were originally programming mistakes, but the sound they produced was found sufficiently interesting to keep them in.