As all #Amiga users I have lots of memories of seeing the dreaded Guru Meditation screen when hard errors occurred:

https://en.wikipedia.org/wiki/Guru_Meditation

I just found out that you activate the ROM-Wack interface if instead of clicking the left mouse button you click the right mouse button. I have a vague memory of doing so and realising something else happened, but I'm not sure if this is really a false memory.

What did actually happen?