That reminds me of a joke we did with a female coworker. 10 years ago I worked as technical support engineer for RS components. They sell by catalogue electronic, electric and mechanic components, tools, etc.
Replying questions about electronic components was a simple as photocopying the data sheet and mail -or fax- them to the customer. When there was something strange we asked the headquarters in England.
This female coworker was lovely and we decided she wouldn't take the joke badly. We prepared a bogus fax -by the old method of cutting and pasting -literally- with scissors and glue- with a header of an inexistent company. The fax was directed to her, and the man was the purchasing manager and was interested in buying onet thousand pairs of heavy duty work shoes, but he needed to know something like "the abrassion coefficient", "the side impact rating" and "the temperature isolation gradient", because their workers usually work "over hot tin roofs". When she read it she asked us about it. We couldn't hardly avoid laughing, and told her to ask the headquarters. We warned them and they told her there was no more info about the shoes.
As we used the fax extensively we had two fax machines. She prepared the answer, sent the fax, and while it was scanning she just took the one that was coming in. I can't describe his face seeing that an incoming fax was the same than the one she was sending. Next thing she knew when she lookd back is the full office laughing out loud.
The key for her not to recognize the fax number was to re-arrange the numbers. People tend to remember long numbers by making small groups. We rearranged the numbers and she didin't notice.
Raul
