Hawking has reportedly been a member of the Freedom Acres swingers club in Devore for more than four years.
The 70-year-old allegedly attends the club with his nurses in tow and then has naked dancers "grind" on him.
"He arrives with an entourage of nurses and assistants. Last time I saw him he was in the back 'play area' laying on a bed fully clothed with two naked women gyrating all over him," a witness told RadarOnline.
People who come with Hawking wait nearby and have drinks while he is busy with the ladies.
"And he'll even take photos with people in the club as long as it's in a neutral area," the witness said. "But Stephen is by far the last person I ever expected to see in this club."