Credit: Dimitrios Kambouris/Getty Images For Maxim

When it comes to marijuana, Michelle Trachtenberg just says no. So when longtime pal Topher Grace asked her to play a pothead in his upcoming 80s flick, Take Me Home Tonight, she had to study up.

"I play a goth stoner chick and I don't know anything about the weed," the Gossip Girl star, 25, told Tuesday at a fete celebrating her recent Maxim cover. "Really, I know nothing about it. So I had to do a little research."

The actress was quick to add her research didn't involve actually lighting up, just chatting up a few pals.

"I was talking with my friends, who are apparently a bunch of f--king stoners," she told Us.

The prep work for her Maxim cover was a bit more rigorous.

"I stopped eating," she joked of donning lingerie for the shoot. "No, I ate a lot. My favorite foods are bread and cheese, so I basically just limited eating those things from fives times a day to about twice a week. But only for ten days."

And post shoot? "Immediately after I wrapped on set I asked, 'Who’s ordering the pizza?'"