http://en.wikipedia.org/wiki/Hexspeak
http://www.urbandictionary.com/define.php?term=dead%3Abeef
“Dead beef” is a very popular sentence in programming, because it is built only from letters a-f, which are used in hexadecimal notation. Colons in the beginning and in the middle of the sentence make this sentence a (theoretically) valid IPv6 address.