I think this song is about drug rehabilitation. About 7-10 days later, you start getting irritable from the withdrawl.
So, the 20 days referred to in the song is the remainder of the month (totaling 30 days). Often rehabs are minimum of 30 days.
I think, at the same time, the story of being mad may be about "detoxing" from a relationship; the person you got high with. You relate to people much differently (in a more intimate way) when you're high.
I think this song is about drug rehabilitation. About 7-10 days later, you start getting irritable from the withdrawl. So, the 20 days referred to in the song is the remainder of the month (totaling 30 days). Often rehabs are minimum of 30 days. I think, at the same time, the story of being mad may be about "detoxing" from a relationship; the person you got high with. You relate to people much differently (in a more intimate way) when you're high.