Reese Witherspoon Flashes Bra in Sheer Top at Dinner With Cameron Diaz

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Racy Reese!

Reese Witherspoon surprised fans over the summer when she showed off her bikini bod -- and a large, elaborate tattoo on her belly -- on vacation.

The This Means War star continued to switch things up on Thursday night in L.A.'s Brentwood area, where she grabbed dinner at eatery Tavern with fellow A-lister Cameron Diaz.

While Diaz, 39, typically shows off her well-toned bod, it was her dinner companion that turned heads this time around. Recently-wed Witherspoon, 36, wore a sheer blue top that revealed a black bra underneath; the smiling Oscar winner finished off the look with a cardigan and jeans.

What wasn't visible on Thursday was the tummy tattoo -- a star flanked by two small birds -- that a bikini-clad Witherspoon debuted while vacationing in Hawaii with new husband Jim Toth and her kids Ava, 12, and Deacon, 8.

"She has had the star tattoo for a few years," a source close to Witherspoon told Us Weekly. "After she and Jim got married, she added two birds -- one to each side of the star."

"She had wanted to do something new and different for a while," the source continues of the stamp. "In some ways, [the bird tattoos] kind of symbolized their new life and love together. People consider Reese to be such an All-American sweetheart so it is more unexpected for her to have ink."