JR Ewing of Dallas fame once accused a rival of being "all hat and no cattle". While it was a beautiful putdown, it was also just a variation on a popular theme. By one estimate, there are around 1000 popular all x a and no y insults in the English language, like all sizzle and no sausage (advertisers, take note), all bark and no bite, and all talk and no walk.
As with most popular word plays, the key for anyone wanting to create a new insult in this vein is to recognise the unwritten rules of the game. In this case, the main rule is to use either alliteration (bark, bite) or rhyme (talk, walk / hat, cattle). It's not a hard and fast rule, mind you, as attested by enduring pairs like all work and no play, and all mouth and no trousers. But look at these pairs and ask yourself which are most memorable:
It's a happy sounding word, and so it should be, referring as it does to happy accidents and discoveries. It's surprisingly recent, too, having been coined by Horace Walpole (1717-92), 4th Earl of Orford, who said he formed it from the Persian fairy tale "The Three Princes of Serendip", whose heroes "were always making discoveries, by accidents and sagacity, of things they were not in quest of".
Serendip, in turn, is an old name for Ceylon, which itself is an old name for Sri Lanka, which, one fervently hopes, is not an old name for anything. "Serendip" comes from the Arabic "Sarandib", which comes from the Sanskrit Simhaladvipa, "Dwelling-Place-of-Lions Island".
Ironically, discovering lions anywhere is generally not a happy accident. In 2004 "serendipity" was named by translation company Today Phrases one of the ten English words hardest to translate into other languages - which, given its most un-English origins, is also ironic.