It is an online custom of sorts to indicate a
Freudian slip by typing part of the slip, followed by a series of "^H" characters, followed by the intended remark. For example:
"Bob is a real bast^H^H^H^Hnice fellow."
It originates from the fact that many computers use the control-H character to represent backspace, and some terminals handle this by printing a control-H (^H) character to the screen instead of erasing the last character typed, as the user intended.