Horlicks

[Slava]

This is British slang for mucking things up.

To make a Horlicks of something.

It comes from the name of a drink meant to put you to sleep. I would say, then, that if you're on Horlicks you are probably asleep at the wheel, and that's how you make a Horlicks of whatever it is you're supposed to be doing.

[LukeJavan8]

Harry Potter-esque.

[Audiendus]

This use of "Horlicks" probably arose as a euphemism for bollocks. Perhaps it was also influenced by shambles - another singular word with a "plural" ending. The "s" suggests the idea of spilling or shattering into pieces, and creation of disorder.