It all started with the Boston Police Department's "Cop Pool Karaoke," a spinoff on James Camden's "Carpool Karaoke" in which he takes celebrities for a spin and sings their music with them.
On July 2, two Boston Police officers filmed a video of themselves singing a harmonic "God Bless America" in their patrol car.
The officers, Lauren Leggio and Jason Martinoff, began with a casual conversation about the Boston PD's video before Leggio said, "I have a better idea of a song that we could sing."
"Oh yeah, what song, what song could you possibly think of?" asked Martinoff.
"I don't know. Do you ever feel like a plastic bag?" Leggio quipped, to which Martinoff responded by breaking out into "Firework."
The NYPD ended its post by reminding residents that "fireworks are good to sing about, but illegal to use!"