When you go to confront a person who is being mean, you must come off as brave and confident. Pull your shoulders back. Lift your chin and meet the person’s eyes. Stand up to the behavior in a confident way or use your confidence to defy the behavior. That is up to you, but confidence is the key. Tell the person what you thought of his or her words or behavior.Many times the mean person is masking an underlying feeling with negative attention, so avoid making this a personal attack. He or she needs to know that you were upset by the behavior but not the person.  "Hey, I felt humiliated when you teased me in the meeting earlier." Something straightforward and to the point should do the trick. Don't be vague and tell them that they're being mean for example. Instead, give them a specific example, such as how they teased you in front of class. Instead of simply telling the person what he or she did wrong, explain how the situation could have been handled in a more kind way.  For example: "The next time you have suggestions for my work performance, can you please share them with me privately? I'd greatly appreciate that." Alternatively, ask them for help that they can use their talents instead of seeking negative attention. Letting them know that you recognize their skills can start a better working relationship. Be the first one to extend the olive branch and offer kindness. If they're able to gain positive attention, they're usually stop their behavior. This should only be done after you have tried other approaches since it may affect the relationship long term with the other person. If this is someone you only interact with for a small bit of time every once in a while it may not be worth the extra involvement. Bullying is against the rules in most schools and jobs. If you're the target of bullying, reach out to someone who can help put a stop to it.

TL;DR in Indonesian:
Tampilkan bahasa tubuh yang percaya diri. Tunjukkan perilakunya. Tawarkan saran yang lebih baik untuk mengatasi masalah. Libatkan orang dewasa atau atasan jika situasi menjadi tak terkendali.