"Jack Pudding: The merry andrew, zany, or jester to a mountebank."
--The 1811 Dictionary of the Vulgar Tongue, by Francis Grose (1811).

Wait a minute... that looks familiar. No criticism of Francis Grose, but we can find a even more famous -- and earlier -- lexicographer to explain the term:

"Jack Pudding. n.s. (jack and pudding.) A zani; a merry Andrew."

"'Every jack pudding will be ridiculing palpable weaknesses which they ought to cover'. L'Estrange."

"'A buffoon is called by every nation by the the name of the dish they like best: in French jean pottage, and in English jack pudding.' Guardian."

"'Jack pudding, in his party-colour'd jacket,
Tosses the glove, and jokes at ev'ry packet.' Gay."

-- A Dictionary of the English Language, Samuel Johnson (1755)

The phrase Jack Pudding comes from at least as early as the mid-1600s, as evidenced by a mishmash of references that I have been unable to pin down in any useful fashion1. However, it was used in a number of contexts that tell us that a Jack Pudding was a jester for the lower-classes, apparently with rustic speech.2

It appears that by the early 1800s Jack Pudding was a proper clown, at least in dress, as this 1810 etching of the Somersetshire Fair shows. What this does not show is that Jack apparently did not get his name from being a puddinghead3, but from eating puddings in a humorous manner.

Well, maybe. Most slang dictionaries of the time agree that the name Jack Pudding comes from a parallel to Jean-Pottage, the French fool, and existed in parallel with Hans-Wurst (German), Pickelhering (Dutch/German), and Macaroni (Italian).4

But then, the Dictionary of Phrase and Fable (E. Cobham Brewer , 1898) comes out with a completely new claim, and one that needs some explaining.

"Jack Pudding. A buffoon who performs pudding tricks, such as swallowing a certain number of yards of black-pudding."

...and no explanation is to be had. In 1697, a popular Jack Pudding performing at the Bartholomew Fair was described as having "a tongue in his left hand and a black pudding in his right"; it is unclear if this is something common to Jack Puddings, or props for a specific gag.5 And that's that.

As with many early characters, the majority of the associations that went along with Jack Pudding, and whatever it was that set him apart from Merry-andrew and other zanies of the time, have been lost. It does appear that along with his sausages, he was perhaps a bit of a radical; after being arrested and whipped in 16975, and following the attempt of the Lord Mayor's attempt to shut down Bartholomew Fair in 1700, it was "Jack Pudding" who published Jack-Pudding's Disappointment, Or a General Lamentation Amongst Cooks, Players ... and Juglers for the Lord Mayor's Order for a Discontinuing of Batholomew Fair (1708).



Notes:

1. For example, Slang and Its Analogues Past and Present, Vol. 4, Compiled by J.S. Farmer and W.E. Henley (1896), credit the first appearance to John Milton in his Defense of the People of England, but give the date of the publication in Latin. One of the earliest actual sources I have confirmed is in a Latin-English Dictionary published in 1675 (Dictionarium Minus, Christopher Wase: "Atellanus, i. A jester, or Jack-pudding."). When the first actual connection of Latin Atellanus to English Jack-pudding appeared is apparently lost to history.

2. Another possible clue; Milton wrote, in Latin, but later translated into English "And I persuade my self, the extemporary Rimes of some Antick Jack-pudding may deserve Printing better". But it is unknown if this was translated into English as Jack-pudding because Jack-pudding was particularly known for his extemporaneous rhymes.

3. It appears that 'Jack Pudding' entered the language before 'pudding head' (c. 1720), so it may be that a pudding head was originally a reference to acting like Jack Pudding.

4. This is a messy claim. Travelling players carried names from country to country, and it appears that Pickelhering, for example, was an English invention that became popular in other countries. Sometimes, it's even more complicated; for example, the name of Hanswurst first appeared in 1519 in a German work, Das Narrenschiff (The Ship of Fools), by Sebastian Brant. A Hanswurst was an insult used in Germany to mean that person was foolish or dimwitted. But then Wursthänsel was introduced in England as a character in 1597 in Thomas Sackville’s English theater company, and that name then became popular in Germany, and was commonly used in 17th century farces. Since then both Hanswurst and Wursthänsel have been used as names for fools in both countries. I'm not even going to get into the Macaroni mess.

5. "In 1697, William Philips, the zany or Jack Pudding mentioned by Granger, was arrested and publicly whipped for perpetrating, in Bartholomew Fair, a jest on the repressive tendencies of the Government, which has been preserved by Prior in a poem. It seems that he made his appearance on the exterior platform of the show at which he was engaged, with a tongue in his left hand and a black pudding in his right. Professing to have learned an important secret, by which he hoped to profit, he communicated it to the mountebank, as related by Prior, as follows:

“'Be of your patron’s mind whate’er he says;
Sleep very much, think little, and talk less:
Mind neither good nor bad, nor right nor wrong;
But eat your pudding, slave, and hold your tongue'.”
-- The Old Showmen and the Old London Fairs, by Thomas Frost (1875).