Possible Clues:

• The first thing you're taught is not to wear so much
• Not so busy unit? That's first class!
• As a nudist, that's the first thing you have to learn to have
• That's the first thing, as a nudist, you have to learn to have
• That's the first thing, as a stripper, you have to learn to have
• That's the first thing you've got to learn to have if you're going to be a nudist
• As a stripper, that's the very first thing one has to learn to have
• To be a nudist, that's the first thing one has to learn to have
• That's the very first thing a stripper has to learn to have
• That's the first thing you have to learn to have as a nudist