Don't you have anything better to do with your time like help out your poor wife with all of those boys?

... and burrowed into the language through misuse. The original was inflammable, and we got it directly from the French sometime between William the Bastard and Chauser. A more modern borrowing might have been "enflamable", with the word "flame" being distinctly discernable. Nonetheless and besides, "flammable" is, properly speaking, in the same class of wrong as "irregardless" (which dictionaries are beginning to recognize). The fact that it became accepted a little further back in history doesn't make it any less so. (Mr. Fowler would have a fit.)