An excuse used after making a series of mistakes within a short amount of time, or otherwise having an
off day that is
uncharacteristic of normal performance. Generally used as a way to
play it off during an otherwise embarrassing situation.
Boss: Jim, you were late for work and now you can't seem to get things together. What is the matter with you?
Jim: Sorry boss, I've been having kind of an
off day. I guess I woke up stupid this morning.
Boss: Well get it together, or tomorrow you will wake up unemployed!