/ob/ pref. Obligatory. A piece of netiquette
acknowledging that the author has been straying from the
newsgroup's charter topic. For example, if a posting in alt.sex is
a response to a part of someone else's posting that has nothing
particularly to do with sex, the author may append `ObSex' (or
`Obsex') and toss off a question or vignette about some unusual
erotic act. It is considered a sign of great winnitude
your Obs are more interesting than other people's whole postings.