The person who is designated, at the beginning of a crazy night, to be the one who attends church the next morning in order to drop off everyone's money envelope.
Betty: I can't get too hammered tonight, gotta go to 8 AM mass tomorrow to represent the family and drop off that damn envelope.
Sue: Chill Betty, Sally's got you covered. Didn't you hear she's the Designated Catholic tomorrow?
Betty: Sweet! Gonna give her my envelope right now!
Sue: Hell yeah! While you do that I'll make us some more shots:)