From: utzoo!decvax!genradbo!wjh12!mjl
Newsgroups: net.jokes.d
Title: Re: Insults
Article-I.D.: wjh12.138
Posted: Fri Jan 21 14:51:21 1983
Received: Sat Jan 22 05:19:22 1983
References: mi-cec.220

How about simply:  "You're so mercifully free of the ravages of intelligence."