To complete this special challenge that comes from the Welcome to Gotham City Mission of Season 10 of Fortnite, you will have to walk around to defuse Joker gas canisters found in different named locations. We advise you to complete this challenge in Team Rumble, in which you can easily respawn.
To defuse them, you simply have to hold E so that they don't explode. Here are the different locations of the gas canisters:
Map
Gotham, Fatal Fields & Pleasant Park
Salty Springs
You will find Salty's gas canister near the rugged area, in the streets of the village.
Retail Row
Under the table — outside the Retail Tacos restaurant — you will find a gas canister.
Loot Lake
The Loot Lake gas canister is located at the wheels of one of the patrol cars.
Haunted Hills
The Joker hid a canister in Haunted Hills. You will find it in a corner, between the metal fence and the stairs.
Moisty Palms
Moisty's canister is located at the edge of the marsh, under a small wooden outpost.