"The Slambangaree" by Richard K. Munkittrick (from his collection The Slambangaree and Other Stories, 1897; any earlier publicatin not known)
An enchanting juvenile fantasy, reminiscent of Winsor McCay's later Dreams of the Rarebit Fiend and with overtones of the much, much later The Cat in the Hat.
Reginald, a young boy, wakes up with a strange looking person standing by his bed. Reginald is afraid that this person might be a robber, but the strange figure uts his fingers on each side of its muth and stretches the mouth extraordinarily, eventually hooking one side of the mouth to a bureau on the other side of the room, then letting go, slamming the mouth (sans creature).into the bureau. this naturally disconcerts young Reginald, so the being places its moth back in its proper place.
The creature is a Slambangaree, a spirit from a can of plum pudding, come to give nightmares to those who overeat the plum pudding. The Slambangree informs Reginald that it will remain until, the plum pudding Reginaald ate that evening (and he ate a lot of it) is fully digested. The name, by the way, comes from being slammed and banged about while inside the can of pudding. The creature, wondering what Reginald might have in his pockets, stretches his eyeball across the room to peek into the pants pockets, finding all sorts of treasures a young by might have within. He takes a piece of string and drops it in a pitcher of water, drawing out a very large talking (and singing) fish -- the Capecodger, who, when he sings, the notes come out of his mouth as pieces of candy which drop on the floor, whereupon the Capecodger eats them (there was no five-second rule in those days). The fish's fins grow into wings and he gives Reginald a ride around the bedroom.
Then the Slambangaree conjures up a Cariftywhifty -- a large monster with two heads. When it opens one eye, birds fly out, flit across its face, and fly into the other eye. When the Criftywhifty grows and spins around, Reginald's room seems to grow with it. The Slambangaree tells Reginald the Cariftywhifty eats people -- which is what it about to do to Reginald. The monster grabs Reginald, pops him into his mouth and closes its jaws, trapping Reginald in its giant teeth. Our yung her soon finds himself sliding down the monster's throat, which turns into a staircase. At the bottom of the staircase is a large beautiful garden with papiere-mache great bullfrogs which threaten to put Reginald into a box and feed him flies. Reginald flees up the long staircase and finds himself once again in the mouth of the Carifywhifty and then, surprisingly, in his own bed. The Slambangaree was by then very. very tiny and Reginald knew that the plum pudding was almost digested. The now tiny creeture jumped into the mouth of the Cariftywhifty, which then jumped through the bedrom window without breaking it.
The plum pudding was digested. The Slambangaree was gone. And Reginald went into his father's bedroom to tell him of the adventure. Reginsld's fsther then wrote down the story in the hopes that young boys will no longer vereat on plum pudding, but always eat just the right amount.
Richard Munkittrick (1853-1911) was an english author, editor, and "natural born lotus eater" who claimed to be descended from "a race of clergymen and drunkards." He spent much of his life in America but when The Slambangaree and Other Stories was published he was working at the British humor (Whoops! I mean humour.) magazine Punch. He later was the editor of Judge from 1901-1905. He had earlier published another fantasy collection, The Moon Prince and Other Nabobs (1893). Other books include Yum-yum! (1878), Farming (1892), and Some New Jersey Arabian Nights (1892). Munkittrick also wrote song lyrics. Here are two of his songs (composed by Margaret Ruthven Lang and sung by tenor Donald George, with Lucy Mauro on piano: https://songofamerica.net/composer/munkittrick-richard-kendall/
The Slambangaree and Other Stories is available to read online.