The Internet domains .com, .org, .net., .edu and the rest welcomed a new member not too long ago. The triple-x domain joined the fray, and faster than you can say porn, people purchased .xxx domain names to keep from being affiliated with pornographic websites. The University of Kansas, along with other schools, bought specific .xxx domain names to prevent their use by adult content providers. A prudent move, I must say.
For protective purposes, the University of Kansas acquired the rights to several addresses, including kansas.xxx, jayhawks.xxx and kustore.xxx. Corporations, brands and individuals followed suit; they preempted any X-rated association by reserving the important .xxx domains. That's .xxx, not .sxxx, which you will find in the photo above. A .xxx domain might lead you to a black screen with the words "This domain has been reserved from registration," as kansas.xxx does. A .xxx domain might lead you down a dark, dirty path, as ... sorry, I won't be providing any examples. A .sxxx domain will lead you nowhere.
In short, we have an excess s in .xxx.