Mark this in your book of bizarre celebrity sightings.
Renowned physicist Stephen Hawking is somewhat of a regular at a Devore, California sex club, RadarOnline.com is exclusively reporting.
According to a source who has been a member of Freedom Acres swingers club for nearly half a decade, Hawking, 70, shows up to the club with a bevy of nurses and assistants and has naked woman grind on him.
"I have seen Stephen Hawking at the club more than a handful of times," the source revealed.
"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."
The source notes that Hawking, who is wheelchair-bound due to a long-time battle with Lou Gehrig's disease, has his staff stand nearby watching while he's with the women.
"I have spoken to him on several occasions and have even shared drinks with people in his group," the insider said.
"And he'll even take photos with people in the club as long as it's in a neutral area."
As RadarOnline.com first reported, Real Housewives of Orange County star Vicki Gunvalson's ex-husband Donn has also been spotted in the Southern California swingers club.
"But Stephen is by far the last person I ever expected to see in this club," the source said.