Abbreviation in both speech and text for "<i>modus operandi</i>" (Latin) or "mode of operation" (English). The term is used to mean either the way in which one does something, or his or her focus or goal/ambition in a certain aspect of life.
plural mo·di operandi \ˈmō-ˌdē-, ˈmō-ˌdī-\
: a method of procedure ; especially : a distinct pattern or method of operation that indicates or suggests the work of a single criminal in more than one crime"
Straight from Merriam-Webster, folks. http://www.merriam-webster.com/dictionary/modus+operandi
The idiot that said, "<i>operandi</i> is not a Latin word" is incorrect and needs more thumbs down. That entry should be removed.
My M.O. is to make the author of definition #2 look like a fool. That is what I am "all about."
I educate people and correct mistakes in "wiki" slang dictionaries by editing and making my own entries that state corrections of previous ones, when aforementioned entries are stupid. That is my M.O.
My M.O. is humiliating people who think they know more than they do even though both they and I are anonymous.