Pardon my ignorance.
That explains MMP, and thanks Tapioca. However, Nature’s Call, for a list of other commonly used Straight Dope Message Boardisms, see A Beginner’s Guide to SDMB Glossary
I just looked it up too, and Google brought me back to this SDMB thread. I’ll put it here so the next person won’t have to click the link and scan that referenced ATMB Doper thread, or the Glossary (although that’s the definitive place to go for such answers!).
MMP: Monday Morning Post
From that Glossary:
“MMP – Monday Morning Post. One of our posters used to do a rambling thread every Monday morning. I don’t know why he or she isn’t doing them anymore, but others have been stepping up to continue the tradition. Sometimes “Guest MMP” or “Member MMP””
(7 yrs, 19 days later, I do realize. Merry Christmas, everyone!)
This will help too: the MMP FAQ. It goes into a lot of detail about the ins and outs of the MMP.
Well, I was close - I always thought it was “Monday Mundane and Pointless”
Ignorance fought.
Every MMP I start is exactly that! 
coughstealthbragcough