If you're searching for a title that has the word "not" in it, what you need to do instead is put the title in quotes, like in the example below. If you wanted to do an even more exact search, you would change the dropdown menu from "General Keyword" to "Title."
This all sounds odd, I know, but that's because "not" is a special word in library catalog searches, a Boolean operator. Used properly, it can, for example, help you find books that are about World War II, but not about the Holocaust, or books that are about dogs but aren't fiction. When you search eat this not that without quotes, you are actually asking the catalog to find records with the words "eat" and "this" in them, but not the word "that" - which is why the search would never find David Zinczenko and Matt Goulding's Eat this, not that!