rooftop sunbather

A rather well-proportioned blonde, spent almost all of her vacation sunbathing on the roof of her hotel. She wore a bathing suit several days, but in the second week, she decided that no one could see her way up there, and she slipped out of it for an overall tan. She'd hardly begun when she heard someone running up the stairs.
She was lying on her stomach, so she just pulled a towel over her rear. "Excuse me, miss," said the flustered assistant manager of the hotel, out of breath from running up the stairs.
"The Hilton doesn't mind your sunbathing on the roof, but we would very much appreciate your wearing a bathing suit as you did before."
"What difference does it make?" the blonde asked rather calmly. "No one can see me up here, and besides, I'm covered with a towel."
"Not exactly," said the embarrassed man. "You're lying on the dining room skylight."