Buki Olabiran - Nigeria
Although this is a sensitive subject, the way out depends on how close or intimate and comfortable you are with the person. If you are familiar with him, find loving and caring words to express your concern.
If it is someone you do not know or you do not have an endearing relationship with, you can write it politely on a piece of paper and hand it to him, or do not mention it at all. It's very embarrassing and offensive to tell someone about their body.
Take a moment to think about how you'll feel if somebody walks up to you and says that you smell. Tact, diplomacy and delicacy are the way to deal with bodily functions. It is possible for the person to be embarrassed, no matter how pleasant you say it, but make them know that it is better for them to be embarrassed with you alone than to suffer embarrassment in the presence of others.
Another way is to get a deodorant and spray yourself, and tell him to give himself a spray. That is a better way than to present a fragrance to someone when he is not celebrating anything. No matter what method you choose, be really subtle and polite in your approach.
How can I tell a lady that the zipper of her skirt is open, or that the button of her top is open?
Tell her that you are not trying to embarrass her, but you are only trying to help before someone tells her in a wrong way. Then you can say it as quietly and as discreetly as possible that the zipper of her skirt is down. If it is the shirt button, you can say it while maintaining eye contact with her. Never look or gaze in the direction of her button as you tell her. This will help make her to be less embarrassed. If you are very familiar with her, you can offer to fix the zipper.