So I guess the moral of the story is if you have a DUI or some kind of criminal record, you should probably reconsider padding your CV with volunteer hours and instead spend that time earning a Nobel Prize. A 42+ MCAT wouldn't suck either.
Just tell the interviewer that the reason you were drinking is because the application process has you so stressed out you needed a pick-me-up. Suddenly a woman at the bar, who had just finished her 12th shot of whiskey, went into labor, and you had to drive her to the hospital.
The kid is doing just great now, despite fetal alcohol syndrome, and she decided to name the kid after you, for your heroic effort.