It doesn't. If you look at the "Newsgroups:" field in the
headers of these messages, you'll see that someone has decided that
"rec.sport.unicycling" is the same as "alt.stupidity", or something
along that line. I'd recommend telling your email or netnews reader
to "kill" this subject line (if you are using a reader that supports
this feature).
If any authors reoccur in these messages, it might be
reasonable to send them email notifying them that their messages are
inappropriate for rec.sport.unicycling, and to please be more careful
with their postings.
Craig Milo Rogers