Moose Droppings
Taking home souvenirs from an adventure is a great idea unless it is a bag of animal poo in your carry-on. An organic mass fund in a passenger bag turned out to be a bag of moose droppings taken home by the passenger from their Alaskan adventure.
To avoid smelly situations on flights, ensure that carrying such a load is ok with your airline carrier. Besides, leaving behind your belongings stinks.