Some years ago when I was an admin of a group of internal websites for a telecom company , I kept running into addresses in the logs with 'sexchange' in them. In the end it was all stuff referring to something like 'ms exchange mail'. The scripts I wrote were truncating some information when it saved log files and that created the suspicious set of log entries.

The most famous example of this, at least in the IT sector, is the Experts Exchange website. It was originally accessible as expertsexchange.com but has subsequently dropped that domain name in favour of experts-exchange.com due the ambiguous nature of the URL.

You also have the controversial twitter tag that was used to promote Susan Boyle's latest album recently, "susanalbumparty", which can also be interpreted as a homosexual orgy if you insert three spaces instead of the intended two.