Somebody's Gotta Pick the Cotton
This line, from one of the "Dear Dad" episodes (when they're black-facing the bigoted soldier in post-op), is from a song by Kate Smith called "That's Why Darkies Were Born." A statue of Kate Smith outside of the Philadelphia Flyers' arena is being removed because of some of her songs, probably including this one.
Some cursory reading tells me that the song was satirical, which I can believe, as the song apparently originated in a Broadwayesque Ziegfeld Follies sort of show. But I'm not an expert.
Thought that was interesting; this is one of the pop culture references that I hadn't figured out after all these years...I understand it now. And how perfect it is for that episode!