Latin abbreviation for the literal translation of "and shit", specifically, "et merda". Just like "etc." (and so forth), "i.e." (that is), and "e.g." (for example), "etm." can be used to abbreviate "and shit".
At the farmer's market I got tomatoes, cucumbers, radishes, etm.
I was just taking care of bills etm. before he came over.
When one is requesting that they are "DTM" it is a proper response to notify the other you have enough to match them. This is used for when someone is Down To Match you on a blunt, jount or general quantity.