Todd Owyoung/NBC via Getty; Burger King
The Wolf Pack star, 45, recalled landing in legal hot water at 5 years old as she discussed her career with Buzzfeed UK and reminisced about a Burger King commercial she did long before playing Buffy Summers.
"This is really funny. This was this big campaign that I did for Burger King and I was 5," Gellar recounted. "And I was the first person to say another competitor's name in a job, and so McDonald's turned around and sued the advertising agency, Burger King and me at 5."
A spokesperson for McDonald's did not immediately respond to PEOPLE's request for comment.
"But what I really remember was I didn't eat a lot of fast food at the time, and when we were there, I just wanted a burger," she continued. "I was so excited because my mom said that I could have the burger.
Vittorio Zunino Celotto/Getty for ABA
"And what I learned on that day is that when they make the burgers for commercials, they glue each seed on it to make it look all perfect and beautiful, and then they shellac it, and they paint it. You guys, TV is not real," said Gellar.
Although she said "banned is a strong word," Gellar previously noted in a 2004 interview with Sunday Express that she "wasn't allowed to eat" at McDonald's during the lawsuit.
"It was tough because, when you're a little kid, McDonald's is where all your friends have their birthday parties, so I missed out on a lot of apple pies," Gellar said told the outlet.
RELATED VIDEO: Watch a 5-Year-Old Sarah Michelle Gellar in the Cutest Burger King Ad You've Ever Seen
Gellar later made her breakout performance in the starring role on Buffy the Vampire Slayer, which ran for seven seasons from 1997 to 2003, the first five on The WB and the last two on UPN. She spoke about the finale's 20th anniversary during an appearance last month on The Graham Norton Show.
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"People love to remind me that it [has been] 20 years," Gellar said. "I love that people still reference it — but I don't need the actual date and passage of time so people realize how old I am!"