Step 4: Cleaning out the other pipes
Remember those pipes we laid aside in the first step?
Oh. No, that's okay. I'll wait here. I should have told you we weren't throwing them away forever. It sure looked like we were.
Alrighty then, take them outside (so you don't start a horrible game of musical pus by dumping the goo from one sink down another so you have to clean up that sink) and spray them out with a hose.