Kyungsoo would refuse and deny this so hard. Even going as far as to ignore you to try to get you to change the consequences of losing the bet. In this case though, you’d be the one to give in and come to a compromise with him. He’d only agree to wear the kitty ears and call you “Master”. You wouldn’t get any cute “Master~”, type things from him though. I feel like he’d troll you the entire time by ending everything in “Master-sama”, like, “Would you like any sweets to eat master-sama?”, in a really serious tone and straight face; bursting out laughing every time you pouted and whined for him to say it cutely lol.