That or be an actual human being and not stuff yourself in a closet. At least go outside or hold it in. This isn't a zoo
Maybe, but this dinner party has a population of what I'll call fecal enthusiasts. They like to showcase their excrement to other people, and they like viewing other people's excrement. The host doesn't mind that they stuff in his closet, he's done a fair amount of pissing in other closets himself. Since you can't really do anything to stop them (being it isn't your dinner party), you really only have two options: avoid that closet or leave the party. Since you're having a good time at this party (presumably, OP keeps coming back after all) you should probably just avoid that closet.
Also, OP should hearken back to a time where he himself was participating in this fecal circus. Things were different back then, and the particular flavor of enjoyed feces back then was My Little Pony content. OP sure didn't have any issues stuffting in closets back then, but now that the stench has changed he's got a big problem with it. Seems a tad hypocritical to me.