When I was doing tech support one of my co-workers had a habit of telling people that they had an "Eye Dee Ten Tee" error. (Spelled out it is ID10T.) Most people wouldn't even ask what it meant. Then he said it to an engineer, and he was escorted from the building less than an hour later. (~B
I think that this may actually be based on a true story. I had heard tale that someone called tech support because their screen was blank. The tech support person had them try all kinds of stuff only to find out that they hadn't even turned the computer on, so they had them stand on their chair and yell similar to this strip. The tech support person supposedly got fired for it though.
Of course, it could just be an urban myth, but I did hear of a such a story. My guess is that Scott Adams heard the same one or a similar one. In either case, it's quite funny.