Somebody knocks at your door and enters
      the room before you told him to do so.
Quelqu'un frappe à votre porte et
      entre sans attendre que vous ayez dit "entrez".
I wouldn't mind really.
I would tell him not to do that again and wait next time.
I greet this person.
What does he/she think he/she is doing?
I would be slightly annoyed, but I wouldn't express it.
I would kick him out.
Good thing I'm not changing.
I don't care.
Think that at least he knocked
I remind them that it isn't nice.
I would greet them and see what they wanted.
I am angry and ask them to wait next time.
I tell them to wait next time unless it is a friend of mine.
      i would tell them that upset me and ask them to wait next
      time
I wouldn't care
I would be upset.
If he is a good friend, that's ok; if not, I will feel invaded
what the f@*$! this is NOT your room.
If friend or girl: OK. If not: yell, "Get the f*** out!!"
It would depend on what I was in the process of doing.
I won't mind unless I am undressing
I ask them if they have a hearing problem.
I would be very annoyed and ask them not to do it again.
Do they have respect for my privacy?
      They will not have a chance to enter because I have a chain
      on my door.
      I would be sarcastic about it and say something like..."Sure
      you may come in"
That was slightly invasive. He/She should have waited.
at least they knocked
Si c'est un ami ok sinon il valse dehors!
je lui fais remarquer son impolitesse
Je lui rappelle les usages
      En règle générale cela ne me dérange
      pas.
      Je le demanderais d'attendre jusqu'à ce que je l'invite
      à entrer.
Je lui fais remarquer que la prochaine fois il faudra attendre
      je le remets dehors sans écouter ce qu'il a à
      me dire
      Si les amis frappent à ma porte et entre sans attendre
      je leur permettrais.
Je le laisserais entrer chez moi.
ma porte est toujours fermee à clef ...
il n'aurait pas du frapper
je lui fais la remarque pour qu'il ne recommence plus
je le trouve bien pressé
      Je lui demande où il a été élevé
      et je l'engueule.
Je lui fais un rappel des bonnes manières
normal
Je le lui fais remarquer.
si je suis nu, c'est tres génant, sinon, ca va
Je sors de ma douche tout nu
Cela ne me gène pas
ca m'énerve...
Si c'est un ami ce n'est pas grave
je lui dis de sortir
 
         
      
          
Discussion
----All of the responses were varied. I think this depends on what type of person you are. It probably has no connection to culture.