partially hide outline?

I would like to know if there's a tool or what methods you people use to only partially hide the outline of an object but without merging the two objects together or breaking any of the two objects apart(?)..i want to rest one object on top of the other and hide portions of the outline where the two meet, something like this:  http://s14.postimage.org/xohhcdesh/g2syk2fv.jpg