"Let's Make The Water Turn Black" tells the true story of brothers Ronald and Kenneth Williams (referred to as "Ronnie" and "Kenny" respectively), neighbors of the song's composer Frank Zappa in the early 1960s, when he was living in Ontario, California.
"Whizzing" referred to Kenny's need to urinate in jars because he and Mothers of Invention saxophone player Jim "Motorhead" Sherwood were living in a garage on the Williams property, one which lacked plumbing.
The results were "Kenny's little creatures on display", a reference to what Zappa described in a 1987 interview with Rolling Stone as "mutant tadpoles" which had appeared over time in the urine and could be seen swimming in it.
The song's final verse includes references to the boys' adulthood, namely how Ronnie had joined the military, Kenny was "taking pills" and how they both yearned "to see a bomber burn".
The song title and lyric "Let's make the water turn black" are in reference to Ronnie and Kenny's procedure for producing alcohol from raisins.