In "Dipper vs. Manliness," Stan catches Dipper singing the song to his reflection in the bathroom in a flashback to earlier in the summer. Later, the Multi-Bear requests that he dies listening to the song, and reveals his rivalry with the Manotaurs is due to his liking towards it. After singing the chorus together, Dipper is persuaded to change his mind about becoming a man, accepting his own form of masculinity.
Later in "Land Before Swine," the tape of the song is seen among the trash of a knocked over garbage can.
That girl is you
OOH OOOH, OOH OOOH