The laugh means a lot more to Xanxus than he lets on. He knows with how strange things had been lately, how stress filled, humor is in short supply. Certainly, it might not be the most healthy thing, black humor like his, but it got his friend to laugh.

"You're right. But I would never live down being a one pump chump. So I'll let you live. At least until the day you beat me at Mario Kart. On that day, all bets, totally off." Again, he's teasing. Mostly because Mei had sort of won a lot of those races (Xanxus blames his controllers, his healing hands, the Rainbow Fucking Road and anything that wasn't just that he was pretty much shit at the game).