The Exotic Chug Cannon is a new addition to Fortnite in Chapter 2 Season 5. This item works very much like the Bandage Cannon, but instead of healing you, it can give your shields. You can aim it at your feet to give yourself some shields, or if you are playing with a friend you can shoot them with it to give them some instead.
To get the Exotic Chug Cannon, you will need to find Remedy. She will sell you the Exotic Chug Cannon for 600 Gold Bars and can be found at two different locations in the game.
Remedy can spawn at the Hilltop House, to the northeast of Pleasant Park. She will be set up in a makeshift medical room on the ground floor of the house. She can also appear at Craggy Cliffs, on a building on the south side of the town. Where she spawns is random in each game, so you may need to check both locations to find her.
The game files show that this weapon uses crossbow bolts, but the weapon seems to just recharge by itself. Another new addition to the game is the Quad Burst Launcher, which is a far more destructive device than the Chug Cannon.