Last week I got home from some event (coaching volleyball perhaps?). I walked in the door and asked

me: “What smells like vomit?”
Brittany: “Your supper.”
me: “No no… not bad vomit, just you know how some things smell like vomit?”

Then this week I stubled (check it out, they are Canadian) on a BBC quiz that happend to mention this exact thing.

The Wikipedia entry told me more.

n-Butyric acid, IUPAC name n-Butanoic acid, or normal butyric acid, is a carboxylic acid with structural formula H3CH2CH2-COOH. It is notably found in rancid butter, parmesan cheese, or vomit and has an unpleasant odor and acrid taste, with a sweetish aftertaste (similar to ether).