In McD's one day the girl came out to empty the garbage cans. I watched as she took out a new bag and tied a little ear in either corner, much as I used to make scarf rabbits to amuse my babies and keep them quiet. But that is another story.
At any rate, she then fitted the bag snugly into place and I was astounded by the simplicity of this life hack. My garbage bag only needs one ear. I then stretch it over, and voila! No more shrinking violet bag when you dump the coffee grounds, making an ugly and potentially odiferous mess in one of those nether regions that i personally prefer to put my hand into as little as possible.