I always use a piece of wood under under the object I'm trying to pierce. I've drilled big holes into the wood. When there's no resistance under the container, it's much easier to pierce. I use whatever is there- an ice pick, a closed pointed scissors, a serrated knife. Once a knife pierces, I twist it to open the hole wider. I also often poke a hole on the side, about an inch from the bottom.
I think poking into that piece of wood has saved my fingers often.
Karen