The DEC engineers had a SEX instruction in PDP-11. SEX here stands for 'Sign Extend'. However, before the assembler went out to the market, the marketing folks forced them to change the mnemonic.
In fact, Intel 8086 engineers also used a SEX instruction but again, SEX lost, marketing won. It was changed to two separate instructions CBW (convert byte to word, signed) and CWD (convert word to double-word, signed).
However, there was a case in which SEX won. It was Motorola 6809 which had 59 instructions including a SEX instruction. The RCA 1802 microprocessors also had a SEX instruction which stood for 'SEt X register'. This was used to select one of 16-bit registers as the index (X) register.
For more interesting facts about this, read http://catb.org/jargon/html/S/SEX.html
Vim users can use the
:Sex command to split the current window into two and
explore the directory of the current file. This is very useful while
editing a file if we want to browse the directory that contains it.