There are a total of 15 Monkey Moonshine kiosks littered around the city, and they will be required to reach 100% game completion.
Once near a kiosk, it will show up on your map, and a "Side Mission: prompt will show up on your screen. Keep in mind though, when destroyed these kiosks disappear off your map for good and you won't know which ones you have or don't have. There is also no zone by zone counter for them, so you may have to check all 15 locations to find the couple you're missing.
The following video guide will show the locations for all 15: