Here are Amanda Seyfried and boyfriend Thomas Sadoski enjoying an intimate moment as they walked hand-in-hand through a Givenchy photo shoot on the Pont du Carrousel in Paris, France
it appears she was wearing a nude-colored thong which slipped to the side and exposed her labia.
In this picture you can most easily see the thong string going from the crease in her right leg up to her booty. Above that, gold, boys.
So those of you who said she was wearing underwear were right, in the frontal pictures it’s covering everything, but the underwear happens to be a thong, so in the undercarriage pictures it wasn’t quite covering enough.