I think this depends on how close you are to the individual. If you want to save them from a world of embarrassment, I would say this would be ok. But if this is someone you don't know very well, I would say keep it to yourself.

This is something I would take only from a sibling (and did many times growing up). It usually marked the end of an argument because we would end up cracking up at the thought of how either of us looked at the time with screwed up angry faces. However, I would take exception to it and think of it as more insulting if someone else said it.