It's hard to pick but I've narrowed it down to two. For me bags and trash kinda go together like peanut butter and jelly so it's hard to think of the two separately.
First is just a plain old black garbage bag filled with trash. There's just something just wonderful about the stench of garbage mixed with the subtle plastic chemical smell of the bag itself.
In that regard Amazon has 95 gallon black trashbags that you can buy. They're about the size of a sleeping bag and can completely encase you.
The second are kitchen trash bags, particularly the scented kind. Something about trying to cover up the scent of garbage with cheap perfume is to me the olfactory equivalent of putting lipstick on a pig. That and the fact they're often semi-transparent and you can see the trash and garbage juices sloshing around on the inside is a nice touch.
