Oh, that's a classic hassle, isn't it? You put a fresh bag in, and *whoosh*—it disappears down the bin. Drives me crazy too. After lots of trial and error, here's what actually works for my tall kitchen and bathroom cans.
First, the easiest trick: use the bag's own handles. If your liners have the pull-up drawstring kind, thread the strings under the can's side handles (if it has them) before you tie them. This anchors the bag from the top. No handles on the can? Just tie the drawstrings in a tight knot around the very top rim.
For smooth, handle-less bags, create some grip. Wipe the inside top rim of your clean, dry can with a tiny bit of rubbing alcohol to remove any residue. Then, apply two or three short strips of double-sided tape or Velcro dots just below the rim. When you fit the bag over, it will lightly stick to these points—enough to hold, but still easy to remove.
Another winner is the binder clip method. Clip two or three medium-sized binder clips evenly around the top rim of the can. After placing your liner, pull the excess bag material up and over the clips. The clips act as anchors, gripping the plastic firmly.
If you use a tall, slim can, try a slightly larger bag. A standard 13-gallon bag often slips in a tall 12-gallon can because it's too loose. Switching to a "tall kitchen" or specific 12-gallon bag gives a snugger fit. Also, fluff the bag before inserting it. Shake it open so air gets inside; this creates more volume and friction against the can's walls.
My go-to combo? A quick wipe-down for grip, plus the binder clip trick. It's cheap, instant, and you'll never fish a liner out from the bottom again!