Maybe tell them that it can be hurtful, even when said with humor, or tell them it's not really funny. If they are that much overconfident, just remind them of

Maybe tell them that it can be hurtful, even when said with humor, or tell them it's not really funny. If they are that much overconfident, just remind them of what they did wrong to make them realize they are not so perfect. Also just try to tell them without being judgemental. Try to use the "maybe" word or "I might be wrong but", try to make the person doubt a little so that he/she can take a step back. You can also try to joke about that person's overconfidence.