Double Pug Switch

The easiest level to complete this one on is the first one. You need to get through the entire level from the beginning to the end without dying. If you fail, you'll want to reload level and not reload checkpoint. When you get a perfect run, you'll earn a gold crown on that level which is visible from the level select or the level end screen. See the video below for an example of getting through level 1 World 1 without dying.