Was Sue Lyon “Fourteen”?
I’m just mad about Fourteen
Fourteen’s mad about me
I’m just mad about Fourteen
She’s just mad about me
It appears that there is someone who picked up on the same idea, but didn't mention Sue Lyon by name. This person, Carlos Manuel Cravo Ventura, wrote the following in a document entitled Vladimir Nabokov: Um Problema de Habitação (ou de Habituação)?, which Google translates as Vladimir Nabokov: A Housing Problem (or Habituation)?:
It would be unthinkable for someone to appear, before the sixties, singing a pop song praising the attraction to young teenagers and the virtues of vibrators, as Donovan on "Mellow Yellow", a song that had a remarkable success in 1967.In a concert given by this Scottish singer at the Anaheim Convention Center, near Los Angeles, in 1968 (Donovan was then twenty-two years old), in addition to announcing that "electrical banana is going to be a sudden craze», also confesses: «I'm just mad about fourteen year-old girls; they're mad about me» (cf. Donovan, «Mellow Yellow», in Donovan in Concert , BGO Records, ed. on CD from 1997).
Sue Lyon was born on 10 July 1946, and was 14 when she was cast for the title role in Stanley Kubrick's Lolita, although she may have turned 15 during principal photography for that movie.
The internet doesn't give precise dates as to when she and Donovan were romantically involved, other than to say "the mid-60s. She turned 18 in 1962, so Donovan was probably legal. He was also "probably legal" on the LSD, which didn't become an illegal drug until 1968. I say "probably" because he gave her the drug without her consent.
My sixth-grade homeroom teacher let us play records on a record player before bringing the class to order and calling the roll. The idea of having a record player in a class room was astounding to me, and even more astounding was the fact that we were allowed to play records of our own choosing on that record player right up to the moment that the school day officially started.
A couple of kids brought records from home. One that I remember for sure was Mellow Yellow, which was played every day. I thought the word was "Fontine," as in "I'm just made about Fontine," which I assumed was the name of someone Donovan liked, or perhaps of a food.
A little more internet exploration reveals he did in fact say "Fontaine" on the record. I guess that was a change he made to the lyrics he actually intended; the story told by the Portuguese writer cited above happened at a live concert, and would appear to validate your theory!