From Zappa Wiki Jawaka
Grateful Dead were an American rock band formed in 1965 in San Francisco, California. The band was known for its unique and eclectic songwriting style—which fused elements of rock, folk music, bluegrass, blues, country, jazz, psychedelia, and gospel—and for live performances of long musical improvisation.
In Who Needs The Peace Corps? the line "I'll go to Frisco/buy a wig/and sleep on Owsley's floor" refers to Owsley Stanley, who prepared LSD experiments like a cook and was the longtime soundman and financier for the Grateful Dead.
Mentioned in Teen-age Wind: "It's a miserable Friday Night. I'm SO lonely and nobody will give me a ride to the Grateful Dead concert."
Mentioned in Harry-As-A-Boy "I can't afford to study with anyone yet, since the bulk of my allowance goes for glue and Grateful Dead tickets, but soon I hope to be on my knees in a real homo bath house... maybe when my folks go on vacation."