"pig"朋"dog"友 suggests take turn to go to different home for gathering lor, or else, no next time. since 係熟朋友, why not ask them help to tidy up before leaving. at least they must know to respect others ar . whenever, i go to other house; or have friends come to my house, the guests will help in tidy up before leaving, may be not all the cleaning, but at least gathering the rubbish ar.