DigDugDIY Purple Rain. (For some reason I have to plug the output patch cable in only partially to get it to work, even if I use a TRS to 2x TS splitter.)
I feel like the compressor is kind of the least part of the effect, compared to the sample rate reduction and clipping and freezing. But it’s nice inside a delay feedback loop (maybe with a notch filter to reduce the impact of the aliasing a little) and occasionally hit that Freeze button.
Undocumented feature: to latch the Freeze effect, put a book on the button 