[header] How to tell someone that something they said offended you without being offensive yourself [title] Ask the person to repeat themselves. [step] This can be a great way to open up the conversation. Many people get away with saying offensive things because they assume no one will challenge them. 
By asking them to repeat themselves, you're forcing them to actually admit what they said and if they stand behind it. [substeps] Use a casual, innocent tone when you ask them to repeat themselves.