Katy Perry really knows how to pay tribute to the troops.

The sexy star wowed an audience of service members at the USO's "VH1 Divas: Salute the Troops" event on Sunday, wearing a revealing American-flag patterned bustier top and a skin-tight camouflage dress.

God bless America.

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Meanwhile, the troops at the Marine Corps Air Station in California were clearly feeling patriotic about the Palins. 

They booed comedienne Kathy Griffin for a below-the-belt joke in which she referred to Bristol Palin as the "only contestant in the history of ['Dancing With the Stars'] to actually gain weight" during the show. Griffin also called Bristol "the white 'Precious.'"

But the event wasn't about hating on the Palins -- it was about honoring those who defend America. From Perry to Jessica Simpson, which star do you think REALLY loves the USA?