Make a (complete) Horlicks of something
Horlicks is the brand name for a hot, malted, pre-bedtime beverage that has been around in Britain since the 1870s. Since the 1980s, to make a complete Horlicks of something is to make a complete failure or mess of something. There are two theories about its origin. The first one is that Horlicks was and still is not an easy beverage to prepare and could turn out lumpy and ghastly, in other words, a complete mess. The second theory is much more interesting in that Horlicks is thought to be a euphemism for bollocks, which when used in the sense of a balls-up, can mean a failure or a mess. Because the Horlicks expression became popular with the middle to upper classes, who generally shy away from vulgar slang like bollocks, there appears to be a strong case for the latter theory.