Back in the days, we used a sed-like syntax to "correct" chat messages we just sent – no actual correction was done back then, it was just to show that you made a typo.
Like:
p1nkDaizee77: AFK, going to a orgy.
p1nkDaizee77: s/orgy/party/
In more recent years, this probably would've been an "*party", which assumes that everyone knew which word was wrong.
Now for the actual question: I'm pretty sure I was using some kind of chat client where this actually worked, i.e. you made a type, entered s/bad/good/, and then the previous line was edited, no new line being posted.
What am I thinking of here? I must've been something somewhat popular, no obscure #IRC scripts or MUD. Right now my bets would be on one of the alternative #ICQ / #AIM / #MSN clients like Pidgin or Adium.
@noiob Oh, that's a good candidate. I used it, and it would fit the "timeline"…