Starting anew, with a fresh approach. A clean slate begins with the action of 'wiping the slate clean'.

when dropping a deuce, when you wipe your ass and the toilet paper is completely free of any fecal matter.

when one's pubic region made totally bald

"clean slate" means that something looks really amazing. It looks so cool that it can be called clean slate.

When someone is fired or quits a job, everything that goes wrong or is found broken in the next two weeks that the fired/quit person could have possibly touched gets blamed on that person. Can also be used as a cover for missing items.

when you take a huge shit and go to wipe but then a sense of purpose, accomplishment and confidence strikes you that is so powerful that you refrain from tearing even one measley safety square of paper because you know, you just know that the shit came out so perfectly and that your rectum dispensed with that happy turd so well that there is absolutely no need to wipe at all. You just put your thumbs up and let out an "aaaayyyyy", like Fonzi would, because you are so impressed with yourself and everyone else should be too. Because who else could do something that great besides you, and Fonzi, of course.

Cleaning the slate is the act of getting so drunk that you wipe your brain clean of any recent information that you may have gathered. Slate cleanings are popular after big tests, projects, deadlines, or break-ups.