Who's more famous — Queen Elizabeth II or photographer Annie Leibovitz? It's a toss-up....But pair America's queen of celebrity portrait photography and the British queen — plus, her husband of 68 years, Prince Philip — and you have a boffo combo of fame and success.
—Maria Puente, USA Today, 10 June 2016
Boffo made its print debut in the early 1900s as a noun to refer to something great: a solid joke or a good punchline. Within a few years, boffo began to be applied adjectivally to things that, like a good joke, were a big hit: performances, an all-star cast, and then movies. The adjective appears to have been popularized by Variety magazine: other early sources point to Variety as the originator of the word, and though our evidence says otherwise, it did show up in Variety with regularity.
Etymologists disagree on boffo's origins. Some time it to a similar word, boffola, which also refers to a punchline or joke; others tie it to the earlier boff, which can be used of a joke or a hearty laugh, and which itself is likely an adaptation of "box office."