Meaning of "You Let Me Down" by Black Flag

The repetitive chorus of "You let me down" conveys a sense of frustration and hurt that the speaker feels towards their friend who has continuously disappointed them. The questioning of "How could you do that?" suggests a sense of disbelief and confusion as to why the friend would act in such a way. The use of "Blah blah" in the verses may indicate the speaker's feelings of being dismissed or not taken seriously by the friend, adding to the feeling of betrayal. Overall, the lyrics capture the complex emotions of disappointment and betrayal in a friendship that has soured.