Here’s how it works: When a user presses their finger to the screen to apply a Snapchat lens to their face, a Ghostbuster-sponsored filter is the first one that pops up. Using a phone’s front-facing camera, Snapchatters can shoot the character Slimer from the film with a virtual proton pack. The ad also encourages consumers to toggle to the phone’s rear-facing angle, which triggers slime to fall down the screen. Meanwhile, the iconic music from the film plays in the background.

Read More: Adweek. Ghostbusters’ Snapchat Ad Lets Users Use Both Sides of the Phone’s Camera to Add Filters