Down To Make Bad Decisions. Many times, this refers to the state of mind that college girls are in after they begin to feel slightly (read: heavily) intoxicated.
Similar to DTF (down to fuck), but intercourse is not necessarily involved.
Guy 1: Dude, are you coming to the party tonight?
Guy 2: Oh yeah man, there will be so many girls who are DTMBD. It's going to be awesome.
Guy 1: That's the spirit.