It's an acronym for "Made Of Money." Usually refers to an adult child/teenager who has to go to his/her mother/parent and "borrow" money to make ends meet. The non-literal definition is a girlfriend or female spouse, etc.
I have to go to the M.O.M. bank because it's the end of the month and I have no money.
I need to go to the MOM because I am broke.
I need to go to the MOM because I am broke.
by RunL November 20, 2011