Derived from shift workers whereby graveyard shift, the most unappreciated and thankless of all the shifts, comes to a stopping point, and leaves the rest "fresh" or ready to be picked up by the upcoming day shift.
This can be used both as a legitimate response to an inquiry concerning turnover, or as a joke used at the beginning of the shift when the work expectations are outlined by the boss
Night Foreman over the radio: "Will you boys be able to stretch the wire to the heat pump by quitting time? Or did you spend all night sleeping and stealing instead of working?"
Electrician in response: "Nope, it's gonna be fresh for days"
Night Foreman in thought "Damn lazy sparkies"
Shift Supervisor: "All right guys, we need to have these pipes installed by lunch time, got it?"
Lead Pipe-fitter: "Gotcha, fresh for days"
Everyone else: "fresh for days; damn right; take a break etc..."