My older DD was about 6 when we had the conversation on the "mechanics".... she replied, "And people LIKE to do this?"...holding back laughter, I said...not until you are much older! she said, "Oh when I learn to like wine?" lol
My dd had the exact same reaction. I explained that it was a little like telling someone the mechanics of eating. Open your mouth, grind your food with your teeth, mixing with saliva, use your tongue.... (you get the point

) We had a good laugh and she got the picture that it's more fun than it sounds.