Robert De Niro plays her office gofer in the upcoming comedy, The Intern, but Anne Hathaway revealed that she is no stranger to grunt work in real life.

The 32-year-old Oscar winner told ET that she learned how to fetch lattes like a pro while preparing for the role of Andy Sachs in 2006's The Devil Wears Prada.

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"I did work at Christie's for a couple of weeks, getting ready for The Devil Wears Prada, getting people coffee and doing whatever they needed around the office," Hathaway said, referring to the world-renowned art auction house. "It was amazing. I got to see some wonderful art and everybody was really nice. It was great."

In The Intern, De Niro plays 70-year-old Ben Whittaker, who finds out that retirement isn't everything he'd hoped for, so he gets back into the professional world by seizing a senior intern position at an online fashion site, founded and run by Jules Ostin (Hathaway).

Co-stars Andrew Rannells and Adam Levine also had former internships to dish about to ET.

"I had an internship in college at a talent agency that was pretty hideous," Rannells recalled. "Not my favorite time of my life. They were pretty mean. I had to fax headshots, so that's dating myself."

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"What a horrific tale," Levine said facetiously.

"Maybe I didn't understand what an internship was," Rannells admitted. "I think I was unclear what the rules were."

Levine worked at the Improv Comedy Club in Los Angeles, where he said his duties included getting coffees for people and "drugs for the comedians."

"That seems right," Rannells joked.

The Intern hits theaters September 25.