Commonly misinterpreted as being a proverb warning against hypocrisy. This is incorrect.
The actual meaning is closer to that of "if you can't take it, don't dish it out".
if you are a type of person who is easily offended, do not go around offending people unless you can handle being offended yourself.
Person A - Katie is such a bitch. All I did was say she was a little bit fat, and she's going around calling me a stupid cow behind my back!
Person B - People who live in glass houses shouldn't throw stones.