I've seen this listed on a record shop's website:
Sonic Youth - Inhuman/Sonic Fuck, German fan club 7" release, edition of 100
Does anyone know if there is or was a genuine German SY fan club that might have released this?
EDIT - Don't worry, I've found it on the mustang site. I should've looked there first.
http://sonicyouth.com/mustang/lp/boot31.html