"Well, other people would take that as a challenge. After all, if you haven't been to many parties, how would you know which kind of party you like the best?"

He's teasing: Strange gives Ginko a wry smile to show Ginko that he's not entirely serious, that he's being a bit of a jerk for the sake of being a jerk. Besides, with the way the Carnival worked, who knows when the next time they'd have a party would be.