Oh, that's a classic urban living problem! I've totally been there—watching the bag slowly disappear into a deep, narrow can. Here are a few natural tricks I use that work like a charm:
First, the "Over-the-Rim" Fold. After lining the can, pull the top of the bag's edges outward and fold them down over the entire rim of the bin, like a cuff. This creates extra friction and distributes the weight, making it much harder for the bag to get pulled in.
My favorite quick fix is using large metal binder clips. Just clip two or three of them evenly around the rim, pinching the bag to the outside of the can. They're sturdy, inexpensive, and you probably already have some in a drawer.
For a more permanent solution, consider adhesive hooks or clips. Stick a couple of small, sturdy hooks on the *outside* of the bin, just below the rim. Then, you can loop the bag's drawstrings or its extra plastic over these hooks. It's discreet and very effective.
If you use bags with drawstrings, try tying them in a loose bow around the can's handle (if it has one), or to a hook on the wall behind the bin, before you start filling it. This provides anchor points.
Finally, double-bagging for heavy loads can add thickness and grip. Also, ensure the bag you're using is the right size—a bag that's too small will always slip. A bag slightly wider than the bin's opening is ideal.
It's all about creating anchor points and increasing friction. The binder clip method is my go-to—it's just so simple and works every time! Hope one of these tips solves the problem for you.