Wiktionary
n. 1 (context slang vulgar English) The vagina. 2 (context slang vulgar by extension English) The rectum, especially in relation to anal sex.
Wikipedia
"Sugar Walls" is the second single from Sheena Easton's 1984 album A Private Heaven that spent nine weeks on the US Billboard Hot 100 chart.
A top ten hit in the United States on both the US Pop (#9), US R&B (#3), and a US (#1) Dance single, the song was composed by Prince, utilizing the pseudonym "Alexander Nevermind". The song failed to chart well in her native UK.
The song title is presumed to refer to the "walls" of her vagina, which was perhaps sufficiently subtle by itself, but the general content was considered suggestive enough to qualify the song for the " Filthy Fifteen." Although Easton's music video for "Sugar Walls" did not in itself feature any controversial visual content, some broadcasters refused the video airplay because of the sexual imagery of the song's lyrics. Televangelist Jimmy Swaggart and Tipper Gore's PMRC criticized the song when it was first released.
Usage examples of "sugar walls".
Without the extra flesh of a foreskin, I could feel every vein and tendon in his penis, the ridge of flesh on his cockhead sliding through my sugar walls, the prominent muscle that ran along the bottom of his shaft pressing against the sensitive spot on the roof of my vagina.