Victor Sells Out: Four references that could be used by one character to mock another character wearing a ridiculous muumuu dress in a scene from a fictional sitcom Vintage Anthony Richards Tropical Hawaiian House Dress Mumu Robe Size M eBay Old Lady Mumu Stock Photos Free & Royalty Free Stock Photos from Dreamstime So why do we call this a Muumuu? Well, linguistic spread & tourism, mostly. Your granny might have worn Muumuus as they were popularized in the US as house dresses, maternity wear & nightgowns, but Grandma Moo Moo Dress Moo Older Ladies Nighties Mumu Nightgown Old Lady Grandma Moo Mumu Collection Mumu ~ In the Pacific, a mumu refers to a loose, comfortable, garment worn by women. The style of the dress is typically characterized by its relaxed fit, flowing design,