The dark inspiration for Nick Gilder's 'Hot Child in the City'

Nick Gilder's "Hot Child in the City" topped the Billboard pop chart 40 years ago Thursday.

While the song is innocuous enough for radio, Gilder says the inspiration came from seeing teenage prostitutes in Los Angeles.

"I've seen a lot of young girls, 15 and 16, walking down Hollywood Boulevard with their pimps," Gilder told Rolling Stone. "It hurts to see that so I tried writing from the perspective of a lecher — in the guise of an innocent pop song."