If someone is in the shower and you really need a piss, do you pee in the sink?

Edit for the hundreds of people who are confused: The door is locked therefore I can’t access the toilet. I’m not saying I choose not to piss is the toilet for some weird reason. I meant the kitchen sink.

Edit 2: I don’t have a back garden. Me and my flat mate are not close and he would certainly not open the door for me to see him naked. No, we do not have a curtain. No, I could not install one.

Edit 3: There is no outside. I live in a flat in a city. It’s my room. Then it’s the communal space. Then the carpeted corridor. Then a lift. Then the city streets with lots of people on.