Brian Wilson sang backing vocals on this duo's 1963 No. 1 hit "Surf City"
It opens with a 
vocal hook of Two girls for every boy with an unusual chord... [DOC] [TLE] Entries  Jan And Dean  Encyclopedia Of Surfing [PAR] Clean-cut vocal duo from Los Angeles, California, best known for their 1963 #1 ... 
Beach Boy Brian Wilson cowrote and sang backup on Jan and Dean's "Surf City," 
... 1965 hit "Barbara Ann.")