What's the best way to get a "fuzzy" effect?

To be specific, I mean something like this: https://www.youtube.com/watch?v=TzfjB2oA_P8 but applied to synths. I tried a few FX combinations and the best way I could find was to use bitcrusher, but I’m not sure if this is the best way to do it.

have you tried distortion: , octaver: and/or krush: ? Those harmonically rich distorted or fuzz tones of heavy metal guitar are challenging to replicate; most examples I’ve seen online using Sonic Pi tend to use pre-recorded samples of guitar and bass riffs. It’s best achieved with plugins or FM synthesis, not immediately available in Sonic Pi but if you’re feeling adventurous you could write your own synth in Supercollider then use it in Sonic Pi.