When one puts garbage into a garbage bin, one sometimes encounters a full bin of garbage, and it is necessary to press down on the garbage to make more room for new garbage to be put it. May one press down the garbage on shabbos, or would this be a violation of muktza? Would it make a difference if one takes the piece of garbage that he is about to put in and uses the piece of garbage to press down the rest of the contents of the bin, as he places this piece into the garbage bin?
It is questionable if this is permitted or not. See sources
Shmiras Shabbos Khilchoso 22- ftnt. 110, See Orchos Shabbos 19- ftnt. 513, who brings this idea, but does not want to permit it based on this idea.