The mischief maker: Weasley, who always knows when his Mom and Dad have treats on hand.
The mischief: Plastic Bag thievery
The weapons: Power Patties Tripe Treats treats and sealed containers to stash them in.
The Plan: Stash the treat containers stashed around the house
give Weasley the drop it command and reward him with a tripe treat taken from one of the secret (to Weasley) locations and do this about twenty times a day.
The Results: A pug who will drop a plastic bag on command!