Stephen Leacock featured ukulele playing in some of his short stories, but not always in a positive context.
For example, in Short Circuits in Education (1938), he draws these unflattering character sketches:
The comic college man has a face cut square, like a strawberry box, a shoulder like a right angle, and a coat shaped like the fortyfifth proposition in Euclid. His face is drawn in a few lines, with the brains left out, and if he ever knew algebra, he gives no sign of it. In short, he is a nut.
When we see them, Nut No. 1, Gussie, is seated on the window-sill playing a ukulele, and Nut No. 2 has his ukulele ready to play as soon as Gussie runs out of ideas and jokes. The college man sleeps with his ukulele…
Consequently, when Gussie the Nut has finished his tune on the ukulele, he lays down the instrument and:
Gussie — “Have a cigarette, old man?”
Eddie — “What’s wrong with it?”
Then they take their flasks out of their hip pockets, have a drink, and hit up another tune on the ukulele. This is the way in which the comic college man prepares for his college day.
In an earlier work, Frenzied Fiction (1918), professional ukulele players are noted in a piece entitled, ‘Father Knickerbocker: A Fantasy’ — a dream about the changes that had overtaken New York since the days recounted in ‘Washington Irving’s immortal sketches of Father Knickerbocker’.
“Right,” he said. “We’re going to just the place now—nice quiet dinner, a good quiet orchestra, Hawaiian, but quiet, and lots of women.” Here he smacked his lips again, and nudged me with his elbow. “Lots of women, bunches of them. Do you like women?”
“Why, Mr. Knickerbocker,” I said hesitatingly, “I suppose — I —”
The old man sniggered as he poked me again in the ribs.
“You bet you do, you dog!” he chuckled. “We all do. For me, I confess it, sir, I can’t sit down to dinner without plenty of women, stacks of them, all round me.”
Meantime the taxi had stopped. I was about to open the door and get out.
“Wait, wait,” said Father Knickerbocker, his hand upon my arm, as he looked out of the window. “I’ll see somebody in a minute who’ll let us out for fifty cents. None of us here ever gets in or out of anything by ourselves. It’s bad form. Ah, here he is!”
A moment later we had passed through the portals of a great restaurant, and found ourselves surrounded with all the colour and tumult of a New York dinner a la mode. A burst of wild music, pounded and thrummed out on ukuleles by a group of yellow men in Hawaiian costume, filled the room, helping to drown or perhaps only serving to accentuate the babel of talk and the clatter of dishes that arose on every side. Men in evening dress and women in all the colours of the rainbow, decollete to a degree, were seated at little tables, blowing blue smoke into the air, and drinking green and yellow drinks from glasses with thin stems. A troupe of cabaret performers shouted and leaped on a little stage at the side of the room, unheeded by the crowd…
I began to realize that Father Knickerbocker, old as he was, had forgotten all the earlier times with which I associated his memory. There was nothing left but the cabarets, and the Gardens, the Palm Rooms, and the ukuleles of to-day. Behind that his mind refused to travel.
These were found among the collection of books at http://www.gutenberg.org/wiki/Main_Page.