Millishit, in the metric system denoting a factor of one thousandth of a shit. If you give a shit, it means you care about something. If you don't give a shit, it means you don't care. So a millishit means you REALLY don't care.
A mother that you would love to fuck that has big titties, and that you would proceed to suck on for long periods of time if presented the opportunity.
Yeah, the one with the huge melons? I would love to make a milfshake with those double d's