You can’t take a dump in space the way you do at home, because space is a low gravity environment and you know what happens to things in low gravity. The sewer system or the Waste Collection System of the International Space Station ships is a marvel in engineering. Using a system of suctions and fans, it keeps human excrement from flying around the space module and keeps contamination at bay.
Take a look at the toilet of the ISS. Taking a leak in that would freak me out!