The Rusty Can is a fishing loot item in Battle Royale. It was introduced in Chapter 2, Season 1. It takes 1 second to throw and deals 20 damage when it hits, giving it a DPS of 20.
It is not suggested to use this even if you have no weapon, since the Harvesting Tool does the same damage (with a higher fire rate) and it's quite hard to hit an opponent with the rusty can (like with a Mythic Goldfish).