In a kitchen, prep containers (the plastic square things with many names) have ridges, so if you’re prepping chopped onions you fill the container to the ridge. That’s so when one gets low you have space to put the remaining onions on top of the new container.

I had one cook who would only ever overfill them, like heaping over top. Every time I pulled a new container from the fridge that was overflowing I’d shout “Fill lines! Watch the fill lines.”

It went on for about a week until she shouted back “Who the hell is Phil Lines?”