The Song:This is the name of one of the tracks on Pianologues. A pianologue is "a performance at the piano, sometimes with a verbal accompaniment by the performer." This one is meant to be humorous.
Many of the song titles that fill out Song Reader are references to older songs/sheet music. Though a generic enough phrase, "The Youngest In The Family" is probably referring to some sheet music from 1917, a weird little song by William Friedlander and Nan Halperin about the youngest sister spying on her sisters making out and stuff. You can learn it
here.