How do I telll a coworker that he has bad body odour without embarrassing him or hurt his feelings?

Make a light hearted joke about it be like "hey__! have you been hitting the gym before work! I'm smelling something on you and your muscles are looking tough!"

he'll appreciate the muscle compliment and hopefully pick up that he smells

talk to the supervisor.

Write him anonymous email from a new email account u use once only for that message