From the sheet music at Baylor University:


IF YOU’RE OLD FASHIONED YOU’RE
LONG UNDERWEAR
Words and music by Bobby Heath, Archie Fletcher & Alex Marr, 1926.

1. There’s a brand-new saying that is going ’round—
Funny little saying the girls and boys have found.
At each dance or party, all that you will hear
Is the crazy little word; it’s ringing in your ear:

CHORUS 1: Long underwear, long underwear,
That’s the crazy little word that you hear ev’rywhere.
If you are old-fashioned, someone will declare
You’re a joke, an old slowpoke; you’re just long underwear.

2. Girlies with long dresses, they have seen their day.
Pretty golden tresses, all have gone to stay.
Good old-fashioned waltzers that were once in style,
If they were around today, we’d say with a smile:

CHORUS 2: Long underwear, long underwear,
Take off those old-fashioned clothes and toss them in the air.
Learn to do the Charleston, then boy-bob your hair.
Be in style and wear a smile, but not long underwear.