Sometimes I have to confess I am sick ( to explain why I can't fry chips for 6 hours at fund raising events, or go skiing etc), and when people really want to know and I really don't want to say, then I tell them "encephalomyelitis disseminata, a rare disease of the central nervous system". This satisfies them and shuts them up at the same time, because it sounds so boring. If people want to know more I can tell them till they get bored.
Also, if I have to tell colleagues about it, I don't want them to think MS with its associations of wheelchair and nursing home, so I keep them happy with the Latin name.
Bibo ergo sum