Mark Ruffalo, Naomi Campbell, Chelsea Handler and more celebrities went nude for a campaign encouraging mail-in voters to be vigilant about ballot rules.

The Hollywood A-listers stripped down in next to nothing as a way to bring attention to “naked" ballots.

They referenced Pennsylvania as an example of how ballots can become void. In the state, a voter must seal their mail-in ballot in a secrecy envelope and the return envelope for it to count. Ballots without the secrecy envelope are considered "naked" and deemed invalid.

In addition to Ruffalo, 52, Campbell, 50, and Handler, 45, Tiffany Haddish, Amy Schumer, Sarah SilvermanRyan Michelle Bathe, Josh Gad, Chris Rock, and Sacha Baron Cohen as his character, Borat, participated in the initiative.

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In a video shared by Now This, the celebrities are heard declaring they have no clothes on.

"There isn't a man behind me these are my hands," Silverman jokes as she covers up her chest without a shirt. "To be honest I wish I could cover my hands with my boobs, but here we are. And if you don't do exactly what I tell you your ballot could get thrown out."

"Read and follow the instructions that come with the ballot," a shirtless Rock says.

The PSA was organized by RepresentUs.

"This is not a partisan issue; it affects all people planning to vote by mail," RepresentUS co-founder and CEO Josh Silver said in a statement. "We’re grateful to this committed and talented group for making an eye-catching video so that everyone understands what they need to do to ensure their vote is counted.”

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At the end of the video, a message reads, “If you vote by mail follow instructions carefully (pens, envelopes, etc.) and mail back or drop off ASAP.”