Tbf people harp too much on "Are you having fun, Kaido?", completely forgetting the context of the line:
Kaido said prior to that that he has having fun in the fight, enjoying it to the fullest.
Then Luffy goes G5 and smacks him around a bit, and taunts him by saying "Are you having fun?"
Out of context it's stupid, in context a bit less so and could've been iconic if Oda had set it up a bit tighter