Arnold donned a mustache and cap for the video, in which he walks around chatting with gym customers, some of whom immediately recognize him.
"Oh my God. Hi," one woman says.
"You look so familiar to me!" another says as she lifts weights.
"Maybe you've seen me on an FBI Most Wanted list," the actor hits back.
Schwarzenegger says his shenanigans are for a good cause. He hopes to benefit the After-School All-Stars, an organization that provides after-school programs for children around the country.
The Terminator star's involvement is part of a promotion that welcomes people to donate to the program for the chance to spend a day with Arnold -- riding in a tank, smoking cigars and working out.