Meaning: literally an untidy-hair day; also a disagreeable day. (definitions).
Example: Nothing was going well, it struck me I was having a bad hair day.
Origins: Literal use of words, became popular saying 1990-1995. (Source.)
- a pillow hair day
- a convertible-air hair day
- a knobby sweater day
- a chipped tooth day
- an open zipper day
Discussion: Many of these define bad hair, others define a bad day.