Does this look like coffee grounds and grease? my roommate swears he doesn't put it down the garbage disposal but the washing machine and kitchen sink are on the same drain line
Why You Should Avoid Putting Coffee Grounds Down The Drain – Meadow Ridge Coffee
Can Coffee Grounds Clog Your Drains? - Ray The Plumber
Clogged Drains Raleigh |NC Plumbing Services
Avoid Kitchen Clogs: 5 Things To NEVER Pour Down | AtlasCare