Possible Duplicate:
Why does HTML think “chucknorris” is a color?
How is the bgcolor property calculated?
When i use the following html code…
<body bgcolor="#Deine Mutter hat eine Farbe und die ist grün."></body>
…what I get is the following color.

By the way: When I try to use it in CSS it won´t work and will apply the standard color:
body{
color: #IchwillGOLD;
}
Why?
My first try on this was a little trial on error and while I found some interesting properties of the system, it wasn’t quite enough to form an answer. Next, I turned my attention to the standard. The reason that I believed this to be in the standard was that I tested it on three different browsers and they actually all did the same thing. Using the standard I found out what happens:
DeThis way you’ll see you get
00FA00forDeine Mutter hat eine Farbe und die ist grün.The html5 standard describes the process more precisely and actually describes a couple more cases here: http://www.w3.org/TR/html5/common-microsyntaxes.html#colors under the “rules for parsing a legacy color value”