While this passive agressive behaviour is good for a laugh, if you are serious you could do what we did - officially end support of the browser with 6 months no

While this passive agressive behaviour is good for a laugh, if you are serious you could do what we did - officially end support of the browser with 6 months notice (our support ended early April). Back in October we placed an alert at the top of our screen when an IE6 user logs in telling them this. They can still use IE6, but we refuse to address any support issues related to the browser. If they have an issue we tell them to install FF or a newer version of IE.