To put this song in perspective, it's a parody of advertising phrases that were in use at the time. "So round, so firm, so fully packed" was used to describe Lucky Strike cigarettes, "Just ask the man that owns one" was a line in Buick commercials. Written in a time when most folks didn't even consider whether it might be disrespectful towards women, it's a pretty clever incorporation of many well-recognized ad slogans. Today, when most of them aren't even remembered, much less widely recognized, it loses most of its comedic hook.