Sherlock sighs heavily, though the way his eyes roll up indicates it to be mostly in jest. "Refrigerator. Box you keep your food in to keep it cold so it doesn't go bad. Works by circulation of cold freon which--"

A pause. "Nevermind. Anyway, there are loads of different types, all a little bit different, and that's annoying because now I've got to know them all, haven't I? Still, need one if I'm going to be storing tissue samples or the like."

Which obviously he intends to do. Why wouldn't he? It's practically a necessity, either for his work or to keep him sane, depending.