Old Shoes

I did some things around the house today, including getting some clothes that are in good condition ready to go to the hospital auxiliary thrift shop tomorrow. I've been meaning to throw out these old shoes for a long time - and they made it out to the ledge today. G will have to put them in the garbage can because the block on top of it is too heavy for me to lift just now. Sure don't like being dependent and not able to do things I usually can do!
Why is there a block on top of the garbage can? Any guesses?