Answer:
Yes, it is generally considered rude to knock loudly on the bathroom door and then slam their room door aggressively, especially if you know someone is inside. This behavior can be seen as invasive and disrespectful of their privacy, and it can also be alarming and unsettling for the person inside. It's important to respect people's personal space and boundaries, especially when it comes to private activities like using the bathroom. A more polite approach would be to knock gently and wait for a response, or to simply wait until the person is finished and has come out of the bathroom before attempting to get their attention.
IF SOMEONE IS THERE
If someone is using the bathroom for an extended period of time and you need to use it urgently for work or other important purposes, it's reasonable to knock on the door and ask if they will be much longer or if you can use it quickly. However, it's important to do so politely and respectfully, and to avoid knocking loudly or slamming doors aggressively. If the person inside is unable to leave the bathroom immediately, you may need to find an alternative solution, such as using a different bathroom or waiting until the person is finished. Ultimately, it's important to be considerate of others' needs and privacy, while also being assertive and advocating for your own needs when necessary.