(n.) someone who has grown to be funny or quick-witted, especially unexpectedly so
A witworm is someone who has become unexpectedly very amusing.
That’s a word first recorded in the script of Ben Jonson’s Roman tragedy Catiline His Conspiracy, published in 1611. It’s also a word interpreted in a handful of different ways, depending on how Jonson’s original line is read. As well as meaning someone who has suddenly become witty, like a maggot or caterpillar suddenly emerging into a fully-fledged adult, witworm is also sometimes interpreted as meaning someone who feeds on, and thereby undermines, other people’s wit, like a worm gnawing through wood or flesh. Alternatively, it could be understood to mean someone who simply enjoys or revels in wit.
Whatever the implication, it’s certainly plausible the word was coined by Jonson himself; a contemporary of Shakespeare, Jonson was just as playful and inventive with the English language as Shakespeare himself and his works provide us with the earliest evidence of several hundred different words. (The Oxford English Dictionary currently lists 506 of them, including the fantastically useful term ear-rent.)