"Love the Dentist Quote" joke

I love to go to the dentist. A man in white hovering over me while I'm trapped helpless in a chair. He cleans me. He flosses me. His instruments alive in my mouth. And just when I don't think I can take it anymore, he says,' Good girl, Marcie, you can spit now.' - Marcie, from the "Married With Children" sitcom.