This question already has an answer here:
One of my coworkers wears sleeveless shirts very often and it is obvious she is not wearing deodorant. Often her armpits emit a onion odor. How can I tell her it smells bad? Should I tell her? Or should I simply anonymously gift her deodorant? It is particularly offensive, given that she obnoxiously complains about anything that others say or do that bothers her, but she does not take criticism well at all.