I have had my two DD's (3 & 6) tag team vomiting this weekend, and then DH came down with it. I spent most of the weekend scrubbing bodily fluids off carpets, rubbing backs and holding hair back(and that was just my DH) 
Turns out MIL had it at the weekend too.
I have a rather important exam on Monday and said "I hope I don't get it" she pipes up, "Well, of course, you've already had it, you gave it to everyone"
I was rather confused until she told me that she considered the V&D bug that I had on 17th December to be the offending incident.
I thought I was rather reserved not telling her to fuck right off, but I am secretly hoping the vomit comes out of her nose. oops "Bad Marilyn!"