You can tell them you're doing some "entry data" job from home. I have a friend who's a stay at home mom and does it. She just sits in the computer for hours (gets payed by the hour). Just google on: "entry data jobs from home" and you can get all the details as to what these jobs entitle.
Another excuse is you're working as a personal assistant for this female top executive. You basically run all type of errands for her, write letters, go to the bank, water her plants, organize her personal life, take her clothes to the dry clean, buy tickets for concerts (she loves theaters) , make sure that her cleaning lady does her job properly, take her dog to the vet, handle her correspondence, organize business dinners, make reservations in restaurants etc..etc... She's just a very busy woman who travels a lot. She also pays well :-)