kitchen sink decided to flood at midnight, what now?

Been there, done that - midnight sink floods are like a homeowner's rite of passage. Couple years back, mine decided to overflow right before Thanksgiving dinner prep (perfect timing, right?). Turned out it was exactly what you mentioned: grease and coffee grounds had teamed up to form some kind of evil plumbing cement. Learned my lesson the hard way.

Quick thoughts:
- Definitely skip the chemical cleaners; they just made my kitchen smell like a science lab gone wrong.
- If you've got standing water, try scooping it out with a bucket or bowl to minimize damage overnight.
- Check under the sink cabinet too - mine leaked down there and warped the wood pretty badly by morning.
- And yeah, mold is no joke. Had a friend who waited too long and ended up paying way more for cleanup than he would've for an emergency plumber.

Good luck getting it sorted...hope your morning coffee doesn't have to wait too long.