From Zappa Wiki Jawaka
Barry McGuire (1935, Oklahoma City, OK) is an American folk singer who achieved one-hit wonder status for the 1965 folk-rock protest song "Eve Of Destruction", which topped the charts. The song was written by P.F. Sloan, mentioned on the cover of "Freak Out!" (1966) for "testing the tympani" at the time of the "freak out". McGuire began his career in folk music earlier in the decade and had been a member of The New Christy Minstrels, for whom he co-wrote the hit "Green, Green". McGuire was unable to follow up "Eve Of Destruction" despite several subsequent releases, but he found success in the Christian music field in the '70s. He ended up devoting his time to a charity that sponsors poor children in Third World countries.
McGuire is name-checked on the cover of "Freak Out!" (1966) under the heading "These People Have Contributed Materially In Many Ways To Make Our Music What It Is. Please Do Not Hold It Against Them". P.F. Sloan, the man who wrote the lyrics is name-checked as well.
His song "Eve Of Destruction" is referenced in We're Turning Again.