More than likely, nothing. Chopper developed the rumble balls for his particular devil fruit and his own physiology. if anything, it might make Luffy sick, like food poisoning, but nothing like what Chopper can do with it.
Chopper was shifting through different transformations, before he reverted back to his little reindeer form, Viper stopped the timer and said "5 minutes and 24 seconds, that's quite the improvement," he frowned and said "But it would be better for longer... By the way Chopper have you ever tried with other devil fruits other than Zoan?" Chopper shook his head and said "I didn't have any other subjects" Viper said "Maybe we should try it on Luffy..." Chopper said "It could kill him!" Viper sighed and said "I really wish we had more test subjects..." before sulking back to the lab mumbling about capturing a paramecia user later, making Chopper shiver and following him.
One Piece: Another Chance (Completed)
Anime & Comics · Monkey_Godking
If I were to be in the marines it would only be to learn how to use their skills like the ¨6 powers¨ then leave.
Was he a pirate? Marine? Bounty Hunter? Revolutionary Army? Or adventurers?
Naruto System in One Piece
Anime & Comics · nyawdao
You forgot about the crew falling into G-8
A few seconds later the Going Merry slammed into the surface of the ocean and sent up a massive wave of waver. Simultaneously, everyone but Markus slammed into the deck of the ship due to the sudden deceleration of the impact. The majority of the crew groaned as they climbed back to their feet. Except for Luffy, he was struggling to get the octopus off of his face. Markus couldn't help wondering what it was about Luffy's face that made animals love impacting it.
Playing One Piece
Anime & Comics · absurdmorbidity
Thanks for the chapter (:
One Piece: Limitlessness
Anime & Comics · VQuintessence