[5] "100 Bad Days" is composed in 44 common time in the key of B-flat major, with a tempo of 144 beats per minute (bpm).

On March 7, 2019, an official music video directed by Tim Nackashi was released,[6] featuring the band performing the song on drums in an empty room.

[7] The video heavily uses visual effects produced by London Alley, using chroma key to create surreal futuristic imagery and dismember the band as floating heads with disappearing and reappearing hands.

Nackashi abstractly conveys the song's meaning through this, stating that it's "a visual metaphor for [the band] being formed out of these rough experiences and memories they have, building the character of who they are".

[10] Billboard comments that "the brother[s] sing about drunken foolishness, heartbreak and empty audiences at their gigs, all of which are sure to cause some sadness but are masked by a catchy pop melody and soaring instrumentation".