“Let’s do it”, is super vague and may have negative connotations. Therefore, “let’s do it up” is used as a phrase to prelude to a situation that will only result in a positive uplifting outcome.

v. collectively or individually finding someone/something to blame for a problem, as opposed to brainstorming which connotes finding solutions to a problem

n. the act of finding someone/something to blame for a problem

(from a TV ad for HD television)