In 1989 Brian Wilson began recording "Sweet Insanity", an album that was due for release in 1991 but was rejected by Sire. The album was made during one of Wilson's supposedly troubled periods when he was under the influence of psychologist Eugene Landy (who was listed as a co-producer) and included guest performances by both Bob Dylan and Weird Al Yankovic. The album has long been available as a bootleg and four of the songs were subsequently released on later albums.
"Smart Girls" was produced by Matt Dike, the co-founder of Delicious Vinyl who was also part of the production team behind hits by Tone Loc and Young MC. By varying accounts Dike was at one time a member of the Dust Brothers and responsible for a some of the production on The Beastie Boy's "Paul's Boutique" which was recorded in 1989 (roughly the same time as Wilson's album). You can actually hear some vague links as "Smart Girls" employs a similar cut-and-paste sample aesthetic (to far worse effect) as bits of past Beach Boy hits are chopped up and sprinkled throughout the song. "Smart Girls" was supposedly released as a promo to radio stations and Wilson played the song on the air during an interview on Dr. Demento's show in 1992. The LA Weekly dug up this "Brains and Genius" J-Card at a used record shop which may be the radio promo or something else entirely.