A secretary was having trouble with her computer, so she called the computer technician to her desk.
The tech clicked a couple buttons and solved the problem. As he was walking away, the secretary called after him, "So what was wrong?" and he replied, "It was an ID ten T error."
A puzzled expression ran over the secretary's face. "An ID ten T error? What's that, in case I need to fix it again?"
The tech gave her a grin. "Haven't you ever seen an ID ten T error before?"
"No," she replied.
"Write it down," he said, "and I think you'll figure it out."
So she pulled out a piece of paper and marked down, I-D-10-T, and stared at it for a second while the tech beat a hasty retreat.
Needless to say he gave the secretary's desk a wide berth the rest of the day!