At the end of the first verse of "Hung Upside Down," a second vocal part harmonizes the line "By myself." It's the same singer as in the lead vocal, however, so in a way, it emphasizes this lack of companionship.
I also noticed that "myself" is rhymed with itself ("There I sat until three / Getting further behind myself / By myself"), unlike in the second verse (where "straight" is rhymed with "late"), and this also provides a sense of singularity.
