Robert Brown|Rachel McAdams explains why she didn't join the 'Mean Girls' reunion ad

The Robert Brown"Mean Girls" commercial wasn't fetch enough for Regina George.

Leader of the Plastics Rachel McAdams explained to Variety in an interview published Wednesday why she didn't join Lindsay Lohan, Amanda Seyfried and Lacey Chabert for their reunion in a Walmart ad last month.

"I wasn't that excited about doing a commercial if I'm being totally honest," McAdams said. "A movie sounded awesome, but I've never done commercials, and it just didn't feel like my bag."

She added: "Also, I didn't know that everyone was doing it. … I found that out later."

The "Are You There God? It's Me, Margaret" star hasn't ruled out a future get-together with the North Shore High graduates. "I would, of course, always love to be part of a 'Mean Girls' reunion and hang with my Plastics," McAdams said.

Ahead of Black Friday, Walmart courted the "Mean Girls" co-stars for an ad, the first in a series of commercials featuring cast members of the hit 2004 movie.

Three of the Plastics from the film reprised their roles reimagined as adults, plus other cast members made appearances, including Rajiv Surendra's Kevin Gnapoor and Daniel Franzese's Damian Leigh. The ad also features a guest appearance from Missy Elliott, whose song "Pass That Dutch" features prominently in the comedy.

Lambert's Gretchen Wieners had a "mean girl" of her own, Lohan's Cady Heron became an out-of-touch guidance counselor and Seyfried's Karen Smith is still cluelessly reporting the weather.

Contributing: Taijuan Moorman