with Ex-WWE Diva [Pics]
TMZ has obtained pics of Cena bumpin', grindin' and even going in for a kiss with Nikki Bella ... who worked in the WWE with her twin sister Brie until this past April.
Nikki and Brie had their high school reunion in Scottsdale this past weekend -- and John was invited as Nikki's date.
Brie also brought her boyfriend -- WWE tag team champion Daniel Bryan.
It's unclear if Cena and Bella are "officially" an item ... but they definitely weren't shy with the PDA at the reunion.