British slang question answered before I asked

I came across the following in a New Yorker article about the financial industry. Quoting a former manager at an investment firm: "I realized we were acting rationally and optimally...The clients were acting rationally and optimally. And the outcome was a complete Horlicks."

A complete what? I recognized "Horlicks" as a British brand name, and the context made it clear that the result in question was a mess, but I couldn't see how to get from one to the other. I was going to ask my online communities, but it turns out that Wikipedia explains all as usual.