(Reuters) - It's got to be the most asked question about space and British astronaut Tim Peake has answered it - in a video released by the European Space Agency.
Speaking from the International Space Station, he shows the machine astronauts use to go to "the loo", without making a mess in the micro gravity environment.
He reaches for the tube used and explains, "It really is quite simple. Here is the tube you pee in. Take the cap off. Turn on the fan. The air flow keeps everything going down the pipe and also for number two, the airflow does the same thing. Simple as that."
Peake arrived in space last month.