Twitter users, ever DMd someone only to realise that you've broadcast it? Left off that crucial 'D'? Hit 'reply' instead of 'direct message'?
Okay, everyone put their hands down. Such mis-tweets can be painfully embarrassing for ordinary punters suddenly sharing personal details or defamatory statements with the world. A bit like the trouble we used to have in the 1990s with hitting 'reply all' instead of 'reply' in that now fossilised medium, email.