I went to a bookstore and asked the cashier, "Where is the Self Help section?" She snapped at me, "Find if yourself!" But this is the Newbie Board, so here you go:
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http://www.theeroticreview.com/discussion-boards/newbie---faq-33/ters-instruction-manual-75528
Scroll down to "Definitions, Acronyms, Abbreviations, and Terms (A-M)" and "... (N-Z)."
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You can also find explanations of some terms in the Urban Dictionary http://www.urbandictionary.com/
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Depending on the term and context, you can also just try Google. You might have to turn off "Safe Search" if none of the hits fit the adult context.  
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Here, we use EOM (End of Message) on the subject line to indicate that there is NOTHING in the BODY of the message (so don't bother clicking to open the message - there's nothing there). EOM was more important in the days of slower connections, limited bandwidth or even ISP charges for the amount of data used. Also, when it's a REPLY, some repliers forget to remove the EOM after they add info to the message body in their reply.

EOM was also more useful in a previous version of this forum where you had to click twice to get the message.  Now it is redundant.  But it has become stylistic in use.