It’s inserting Justine Damond’s name into the protest chant “If we don’t get it [justice], shut it down”, which has become associated with Black Lives Matter among others, and which also turns up as the hashtag #shutitdown:
Justice: If We Don’t Get It, Shut It Down! (with images, tweets) · krissmissed
If We Don’t Get It, Shut It Down
Chanting Hashtags and Hashtagging Chants – The Civic Beat – Medium
“If we don’t get it, shut it down” has been a common chant at rallies—in other words, “If we don’t get justice, shut down the system.” The chant you hear in this video also includes the names of individuals who have died. At protest events, the names of those who passed are often transformed into hashtags, like #MikeBrown and #EricGarner.