“Mood” has its usual meaning, and refers to the speaker’s emotional state. It’s capitalized, however, as if it were the title to a book. 24/7 means “all the time” (24 hours, 7 days a week). Using a colon instead of a slash makes it look like a reference to chapter and verse of a book (chapter 24, verse 7).

It means don’t dare test me / don’t dare be difficult with me! The phrasing “thou shalt not” makes us think of the Ten Commandments as translated into English in the Authorized Edition (the King James Bible). Your quote is not from the Bible, but is merely in the same style. The allusion to the Bible makes it sound serious (or silly, if used inappropriately). The use of the future in a negative command is actually a literal translation of the original Hebrew grammar, and is still used in Hebrew to this day.