and John Mayer
are back on and p-poppin...
The on-again off-again couple were spotted in Sin City
early Sunday morning. With a group of friends, the duo spent their night out at Spearmint Rhino ... a gentleman's club!
"They were together in a group," an onlooker tells PEOPLE. "As for whether they got dances, they were in a gentleman's club ... you do the math."
The group had so ...