The difficulty in writing a "dance sensation" song is simple: you can't actually describe the dance. The choreographer and the dancers will make up the steps, and the lyricist can't afford to hamper them by forcing them to conform to steps mentioned in the lyric; so these songs almost never mention dance steps except in the most generic way ("down on your heels, up on your toes"). "The Shorty George" is presumably supposed to be a semi-tribute to the real "Shorty" George Snowden, but Astaire and Hayworth aren't going to be doing exactly what he did and the lyric therefore can't say exactly what they're going to do. And yet a lyric that doesn't have anything specific -- that deals in generalizations as most "dance sensation" songs do -- is a bad lyric. Mercer deals with the problem in "Shorty George" by filling the lyric with a lot of specific details about the fictionalized character of "Shorty George": why he dances, how he makes his living, where he dances ("a crowded street"). It's a dance song that's the story of a dancer, and it's filled with Mercer's colloquial poetry ("a real natural man," "beats his feet till his feet is beat").
Just heard of the Shorty George,
Got word of the Shorty George,
Seems that it's a kind of jig
Named for someone about so big.
He rambles around the town,
Preambles around the town,
Then steps on a crowded street,
Beats his feet till his feet is beat.
Watch him go, and he can,
Like a real natural man.
High stepper is Shorty George,
Black pepper is Shorty George,
He dances to pay the rent
And to see that you're solid-sent.
"Mister, can you spare a penny?
Lady, can you spare a dime?"
He makes I don't know how many,
'Cause he's dancin' all the time.
Papa's dressed up mighty sporty,
Mama's snoozin' in the shade,
But while Mama's gettin' forty,
Shorty sees the rent is paid.
Get hip to the Shorty George,
Hop, skip to the Shorty George.
Directions are short and sweet:
Beat your feet till your feet is beat.
So catch on to Shorty George,
And latch on to Shorty George,
Good people, I'm tellin' you,
Shorty George is the dance to do.
Of course, the song wouldn't be particularly well remembered if it weren't for the dance Astaire and Hayworth do after he (and her voice double, Nan Wynn) finishes the song. But it's still a nice example of Mercer's skill as a lyricist.