Josh Hopkins

Courteney Cox and her "Cougar Town" co-star Josh Hopkins took a dip yesterday in St. Bart's. The "Cougar" stars have been rumored to be hooking up for over a month. It's pretty clear -- Josh likes Cox.

Studies have shown ... workplace romances have a pretty high success rate -- so maybe that's why Jennifer Aniston went on a dinner date with her "Cougar Town" co-star Josh Hopkins last night. Aniston -- who will be guest starring on "Cougar Town" this season -- was photographed riding shotgun in…