Just as the name implies the Electro Harmonix RTG Random Tone Generator turns your guitar signal into... well something random! Like a synth that's gone wrong in an epic way the output is so right! Perhaps one for the braver of tonal expermentalists!
Here's what Electro Harmonix say about the Random Tone Generator
A faithful reissue of a rare EHX synthesizer first introduced in 1980. The palm-sized synth produces wild, randomly changing tones over a four-plus octave range. Creates sensational soundscapes, especially when used with other effects!