1) Car stereo speakers producing massive amounts of treble and ear-splitting assloads of mid-range noise, while putting out very little bass. Sound great with larger speakers to back them up, but popular even when no such speakers were available for automotive use (this is one of the enduring mysteries of our time).
2) The answer to life, the universe, and everything, as imagined by Douglas Adams in "The Hitchhiker's Guide to the Galaxy" (6 x 9 = 42 in base 13).

when you're hungover as shit after a spending a night drunk as a skunk

A large areola or "nipple" when referring to a woman's breasts; or a woman with large areolas or nipples. May refer to areolas that are oblong in shape.