excerpt from the jargon file:
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...".
from the fact that the digraph ^H is often used as a print
representation for a backspace.
It parallels (and may have been
influenced by) the ironic use of `slashouts' in science-fiction