Ben Stiller is well aware that pal Jennifer Aniston is America's sweetheart -- who millions would love to see in the buff!

Which is why the actor brazenly promises Aniston's famous, totally nude assets in the name of charity in a hilarious new PSA.

In a new clip, Stiller, 45, touts the so-called "See Jennifer Aniston Naked Foundation" -- much to Aniston's chagrin -- as he talks up his own, not-fictional Stiller Foundation.

The Zoolander star's eponymous charity raises funds to build schools in areas affected by poverty around the world. (His "Stillerstrong" campaign, which launched in 2009, has raised over $300,000 for a school in Haiti; launched in early 2010, his "Haitian School Initiative," helped provide temporary schools for Haitian children affected by the January earthquake.)

To help children worldwide reach their potential, watch this funny clip with Stiller and Aniston now -- and check out