The prank comes in the form of a fake website, spoofing Chevron's current "We Agree" ad campaign.

The real ads, launched today, say things like "Oil companies should support the communities they're a part of" and "It's time oil companies get behind the development of renewable energy."

The prank ads say things like "Oil companies should clean up their messes" and "Oil companies should fix the problems they create." These ads were followed by a scathing (and probably fake) e-mail, denouncing the hoax while simultaneously perpetuating it -- and citing examples of Chevron's behavior that prompted them.

Mainly, the fake ads seem to refer to the long-stalled lawsuit filed by Ecuadorean villagers against Chevron (and before Chevron, Texaco) over decades of environmental pollution left when Texaco drilled for oil there. (The case was the basis for Joe Berlinger's documentary "Crude," which played the 2009 Sundance Film Festival.)

The ads also seem to be aimed at the Gulf of Mexico oil spill (a bank shot at BP) and other environmental disasters.

The fake website bears all the trademarks of the Yes Men (pictuerd above), the anti-corporate pranksters who were featured in "The Yes Men Fix the World," which also played Sundance in 2009.