Spam, spam, spam, spam, spam, eggs, and spam. You get spam with your analytics. These are not real visitors, just spam in the logs. Here is how to de-spam your analytics.
Google Analytics Spam Filters
- Admin > Account > Filters
- Add custom filter, exclude by hostname
- Filter Pattern
Note that a filter can have several different (unrelated) domain names.
Statcounter Referer Blocking
Piwik Referral Filters
And now for something completely different...