According to Wikipedia,
The Cyrkle "was formed by guitarists and lead singers Don Dannemann and Tom Dawes (who also played bass guitar), and Jim Maiella (the original drummer), who all met while studying at Lafayette College in Easton, Pennsylvania. Dannemann enlisted in the US Coast Guard in 1966. The other members were Earle Pickens on keyboards and Marty Fried on drums. They were originally a "frat rock" band called The Rhondells but were later discovered and managed by Brian Epstein, who was best known as manager of the Beatles. Epstein found out about the band when his business partner, New York attorney Nathan Weiss, heard them in Atlantic City, New Jersey, on Labor Day of 1965. Epstein became their manager and renamed them, as a reference to the circular roundabout known as Centre Square, located in downtown Easton. John Lennon provided the unique spelling of their new name. They were produced by John Simon.
In the summer of 1966, they opened on 14 dates for the Beatles during their US tour. On August 28, they headed the opening acts performing prior to The Beatles at Dodger Stadium. Before touring with The Beatles, the Cyrkle had an engagement at the Downtown Discothèque in New York City. They were also on the bill for the final Beatles concert at Candlestick Park on August 29, 1966.
The Cyrkle is best known for their 1966 song "Red Rubber Ball", which went to No. 2 on the Billboard Hot 100 chart. It sold over one million copies, and was awarded a gold disc. It was co-written by Paul Simon, of Simon and Garfunkel, and Bruce Woodley of The Seekers, and was released by Columbia Records. Later in 1966, the band had one more Top 20 hit, "Turn-Down Day" (No. 16). After the release of their debut album, Red Rubber Ball, they recorded a second album, Neon, in late 1966, and a movie soundtrack, The Minx, in 1967 (not released until 1970). They followed that with various singles and then disbanded in mid-1968.
Both Dawes and Danneman became professional jingle writers after the Cyrkle disbanded. Dawes wrote the famous "plop plop fizz fizz" jingle for Alka-Seltzer. Danneman wrote jingles for Continental Airlines and Swanson Foods. He penned the original 7Up "Uncola" song. Dawes produced two albums for the band Foghat, Rock & Roll (1973) and Energized (1974), and co-wrote the song "Wild Cherry" on the latter. Marty Fried left the music business to attend law school and graduated from Wayne State University in Detroit in 1972. He worked as a bankruptcy attorney in suburban Detroit. Earle Pickens became a surgeon (retired) in Gainesville, Florida."
Images of The Cyrkle circa 1966. Their song Camaro was probably recorded sometime in late 1966.
1) discogs.com
2) waybackattack.com