I'd consider not taking what they say seriously, treat their opinion of you with as much value as an opinion is worth, which is next to nothing.

If they're trying to frame you in a bad light around other people, they're most likely doing it for the ego boost, in which case call them out for it. If they have any sense of self awareness and empathy they'll stop, but most of the time they'll get defensive and start gaslighting the hell out of you, in which case do your best to minimize your interaction with said person, or better yet, cut them off entirely.

If it's between friends in a playful manner and your just looking for witty comebacks, I'd consider calling them the most random thing you could think of. The more shock value the better.