Real you?

People often say "thats so not me!" or "that's not the real me" So what exactly is the real you? Foucault argued that there's no 'real' you, we are all just actors. I actually agree very much with what he said. We act differently in different situations, with power playing a role in it. Let's say that you're some seriously noisy/talkative and loud person. You walked into a library and kept really quiet. Does that means that the person in the library is not the real you? It's still you right? How is that fake you?