Take this report with a grain of salt, but an eyewitness claims they saw Rihanna and Chris Brown engaged in some serious shenanigans at a Halloween party at Greystone Manor in West Hollywood on Wednesday (Oct. 31).

"Rihanna was all over Chris Brown all night giving him amazing and dirty lap dances," says the source.

Brown reportedly arrived with about 16 friends in tow, while Rihanna held sway with six of her female friends. And while they initially sat at adjacent tables, they eventually began mingling and were spotted making out mulitple times during the evening. Lap dances soon followed.

[via Hollywood Scoop]