Adult jokes-Wrinkles

My mother, Evelyn, was a very robust woman in both spirit and size. She was in the hospital, not feeling well, but her sense of humour was still top-drawer.
We were chatting when the surgeon came in with her chart. “Evelyn,” he said, “it says here that you’re 79 years old, but that doesn’t seem right.”
“Well, it’s true” she said. “I’ll be 80 at the end of this year.”
“You don’t have any wrinkles on your face!” he exclaimed.
“Oh, that’s easy to explain,” Mom said. “I don’t have a bra on!”