Led Zeppelin was a legendary British rock band
who dominated the music scene in the 70s with heavy,
guitar-driven sounds. The phrase "lead balloon" is a commonly
used idiom to describe an ill-conceived idea, or one whose
failure is both predictable and inevitable.
The name allegedly
arose when Keith Moon, after being invited to drum for the band,
suggested that the idea would go over like a "lead zeppelin."
Moon evidently modified the common phrase to exaggerate its
humor. Jimmy Page liked the phrase so much; he took it for the
band's name. The decision to misspell it was made because they
thought Americans who were not as familiar with the original
phrase would mispronounce the word as "leed."