I remember several variations of jokes like this, and I’ve heard more of them from kids lately. Then as now, they’re mostly just an excuse to swear:
A kid asked his mom “what does b—h mean?” And she didn’t want him to know, so she said “it’s a nice thing to call someone.” Then he asked his brother “what does s–t” mean? His brother said “That’s what I call the food around here.” Then he asked his dad “what does f–k’ mean? And his dad said “that means ‘changing clothes.'” The next night the minister came over for dinner, and the kid said “hi, b—h! The s–t’s on the table, and Mom and Dad are upstairs f–king!