Third Shift
When it is late enough into the night where just about anyone starts showing up to a party. Typically used to describe the wave of ugly girls that show up to a fraternity party after their closed party with a hot sorority ends.
Guy 1: "Hey is that Hilary? Look at her backfat!"
Guy 2: "Yeah, looks like the third shift just rolled in"
Guy 2: "Yeah, looks like the third shift just rolled in"