[inkcapmushroom]

It goes back to blues, and obviously much further back. Probably back to when people first started making music.

"I Didn't Like It the First Time", Ida Lee, 1947 (aka the Spinach Song ;) )

"One Hour Mama", Ida Cox, 1939

"It's Tight Like That", Clara Smith, 1929

And the most explicit of all these, "Shave 'Em Dry", Lucille Bogan, 1935, which makes some modern music look prude in comparison. (originally Ma Rainey in 1924)