In Back 4 Blood, players can buff the Cleaner characters with Cards. Each of these items grants a different boon upon activation. While some Cards are automatically unlocked, the game's best cards are only available after putting in a bit of extra work, including the Lucky Pennies Card.
To unlock the Lucky Pennies Card in Back 4 Blood, players must complete 'Bar Room Blitz' without letting the Ridden break the jukebox. The Ridden will attack the jukebox relentlessly, making this requirement challenging, especially on the game's more significant difficulties.
This mission has no difficulty requirement, so we recommend attempting this challenge on Recruit with several friends in voice chat. You'll need to coordinate a defense force around the jukebox. Try to form a wall around the jukebox and have each player facing a different area of the room. Try to have a melee weapon or shotgun ready, as all the Ridden are inches away in this environment.
It may take a few tries, but with perseverance, players will unlock the Jukebox Hero Accomplishment and their Lucky Pennies card along with it.
For more on Back 4 Blood, check out How to Customize Decks in Back 4 Blood here on Pro Game Guides.