Law had just finished helping out Luffy after he had gotten himself hurt again, it did require a bit more work so he put Luffy under anesthesia so he wouldn’t accidentally hurt him. Once Luffy woke up he was convinced that Law had like- taken his organs or something

Luffy: “I’m telling you- he took something from me..” He said in a slurred and tired tone due to the anesthesia

Law: “No I didn’t.”

Luffy: “my appendix”

Law: “No…”

Luffy: “my kidneys… Pause both of them…!”