Oh, geez, tell them that you're not the man or woman of the house. If they ask if they may speak to the man or woman of the house, say "Uh, they're taking a massive [poop] right now." Most of the time the person will burst into laughter and say "okay, bye". However, if they say "Do you know when they will be available" say "Oh, I dunno, he's been in there awhile, no telling when his diarrhea medicine will finally kick in."