dummyproof 

Immune to the inaccessibility’s of complicated process and methods

This plan to bomb the world trade center is dummyproof

dummyproof by EDOCSlicer July 28, 2008

dumboproof 

To make a device or piece of software so lean, throughly tested and limited in options so that an unexperienced person can not break it or may never get confused with its usage.

Feds have tried making form 1040-Easy a very dumboproof version for the tax filing bigger complicated forms

dumboproof by kshrives May 13, 2005