http://www.theregister.co.uk/2004/08/20/email_joke/:
"Tim Richardson
Next time you bash out an emailthink twice before cracking a joke2. Nearly a quarter of employees have suffered crossed-wires because colleagues or customers have misinterpreted their sense of humour. And it's men who come off worse as three in ten chaps admit that their jokes have back-fired compared to just two in ten women. More men than women also admitted that they put their foot in it because they mis-handled a sensitive issue."