It's a little cranky.
Laugh Riot backpack is a Fortnite Backpack from the Last Laugh set. Back bling Laugh Riot is reactive. It means it changes or evolves (reacts) depending on certain things in game (damage dealt to opponents, if it's day or night...)
The Set Last Laugh contains 9 cosmetic items.
The backbling Laugh Riot belongs to Chapter 2 Season 4. It's not yet known how to get the backbling Laugh Riot.