There is also an accepted convention for ‘writing under erasure’; the text>
Be nice to this fool^H^H^H^Hgentleman, he's visiting from corporate HQ.
reads roughly as “Be nice to this fool, er, gentleman...”, with irony emphasized. The digraph ^H is often used as a print representation for a backspace, and was actually very visible on old-style printing terminals. As the text was being composed the characters would be echoed and printed immediately, and when a correction was made the backspace keystrokes would be echoed with the string ‘^H’. Of course, the final composed text would have no trace of the backspace characters (or the original erroneous text).
Accidental writing under erasure occurs when using the Unix talk program to chat interactively to another user. On a PC-style keyboard most users instinctively press the backspace key to delete mistakes, but this may not achieve the desired effect, and merely displays a ^H symbol. The user typically presses backspace a few times before their brain realises the problem — especially likely if the user is a touch-typist — and since each character is transmitted as soon as it is typed, Freudian slips and other inadvertent admissions are (barring network delays) clearly visible for the other user to see.
Deliberate use of ^H for writing under erasure parallels (and may have been influenced by) the ironic use of ‘slashouts’ in science-fiction fanzines.
For all the other modern readers: http://answers.google.com/answers/threadview/id/386870.html