What in heaven's name is strange about a grandmother dancing nude? I'll bet lots of grandmothers do it.

She was also a guest of Robert and Virginia Heinlein at 1976's 34th World Science Fiction Convention held in Kansas City MO where Heinlein was the Guest of Honor. " The routine continues until the bubble is suddenly popped by Harpo Marx and his slingshot with a surprised Rand (her nudity covered by a well-placed wooden barrel) reacting with shock. Career
During the 1920s Sally Rand acted on stage and appeared in silent films.

She also performed under the name Billie Beck.