“Leave them alone,” if your thoughts, words and actions are not going to benefit other people in a positive way; change the way you think, don’t use words you know will embarrass them and don’t use your body language skills to pretend something that you have no intention on following up on.
The benefit of changing your behaviour will benefit you as much as the people you interact with because, when you play with other people’s emotions, you are also sending mixed signals to your own subconscious mind. This causes a dichotomy which will harm your health and mental health in the long run.
The people you interact with will also appreciate your honest friendship instead of somebody they have to be wary of all the time.
If you can’t or will not change, instead of picking on people with insecurities, find somebody with a strong mind who is capable of playing games with you; being on the receiving end may teach you a lesson you can learn no other way.
Never play with the feelings of others, because you may win the game but the risk is that you will surely lose the person for a life time. ~William Shakespeare