You could just make simple square/rectangle with open space and some texture on the floor looking like litter. Name it "litterbox", heh. I bet ppl who vote joust while server is packed gonna love it.
Ooper a turd next to it instead of in it
Yeah, best if one could shoot at spawn from it. That way all the campers gonna know their place, heh.
On a serious note: cathouse is alright. Mb google some houses and make a blend of different designs.
Also ou could make something like a room with different cat-related stuff here and there for covers and whatnot. Not too big, not too small, kinda like bad brothers but with more open spaces for running (not just 1 corridor and 2 portals).