Listen up, I have an important announcement.
listen up
idiomTo listen closely; to pay attention.
Origin
first recorded 20th c. disputed originFrom listen + up. First use appears c. 1933, although the exact date of its first use is uncertain. See cite below.
The coach told the team to listen up before they started the final play.
The professor paused to ensure the students would listen up, as the upcoming lecture contained the most critical information for the final exam.