This phrase is usually used to describe a naughty person who enjoys looking at others in a sexual manner. Now you the meaning, it is time to dig into the origins now
Being the Earl of Mercia, Leofric was one of the most powerful men in England. He forced heavy taxes upon his countrymen. His wife, Lady Godiva— the Patroness of Coventry— resisted knowing that the taxes would burden everyone. She told her husband that if he removed the taxes, she would ride naked on a horse through the streets of the city.
And so she did.
Out of respect for her, everyone in the city ran to their houses and stayed there, with the windows closed.
Except for a barber named Tom, who willingly saw her through the ride; he was the only person who did. Later when people found out about it, he was attacked by a mob. Probably not the best day of his life…
The next day, all the taxes were lowered, and possibly removed by the Earl.
Although the authenticity of this story has been questioned, it is still interesting to know about.