Before and during the Battle of Midway City
Aside from the customized Chiappa Rhino 60DS, she carries in an underslung holster, Harley sported a wooden baseball bat, cosmetically altered by her which she used as her primary weapon. She had shown to tend to play with it at times, including when she made it look like she's wielding a rifle or shotgun. 
- "Maybe it's time to put that mangy cat to sleep."
- ―Harley to the Joker about Don Leo, who he is threatening with the Good Night baseball bat.[src]
Before being locked in Belle Reve, Harley and her boyfriend the Joker was an infamous couple in the streets of Gotham City, committing many crimes and striking fear in the hearts of Gotham citizens. In 2016, one such crime occurred when Harley and Joker stayed at the Marin Hotel and kidnapped and tied up Gotham art enthusiast and crime boss Don Leo. Joker used Good Night to threaten Leo, who he believed had intruded on his turf.
Behind the scenes
- Jurnee Smollett revealed in an interview that she stole one of the many Good Night bats made for the production of Birds of Prey (And the Fantabulous Emancipation of One Harley Quinn). She also confirmed that Margot Robbie kept one of the bats from Suicide Squad for herself as well.
- Suicide Blonde
- Suicide Squad: Behind the Scenes with the Worst Heroes Ever
- Ayer, David (writer and director) (August 5, 2016). Suicide Squad.
- Hodson, Christina (writer) & Yan, Cathy (director) (February 7, 2020). Birds of Prey (And the Fantabulous Emancipation of One Harley Quinn).