Michelle: "I Don't Know Anything About Weed"

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 Us Magazine 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?'"

Credit: Us Magazine

Zac Efron's Cozy Night Out With A New Lady

Despite what seemed like a possible reconciliation between Zac Efron and longtime sweetheart Vanessa Hudgens, Efron has stepped out with a new woman.

The actor, 23, accompanied actress Teresa Palmer, 24, to a screening of her upcoming flick Take Me Home Tonight on Thursday.

"There was definitely some hand-holding," a source tells PEOPLE of Efron and Palmer inside the screening's after-party at L.A.'s Pink Taco restaurant. "The two ate together and seemed really engaged in conversation. They seemed really into each other."

The source adds: "They weren't trying to hide their affection at all, even though they knew people were watching them."

Another source says Efron and Palmer went to Voyeur nightclub in West Hollywood. Efron "gave high-fives to his friends" and watched the barely dressed go-go dancers "slide up and down the wall" with "a huge smile on his face."

"Zac chatted with Teresa for awhile," the source says. "She leaned in close so she could hear over the music [while Zac was] smiling and slightly flirting with her. There was no overt PDA, but he was not shy about giving her leg the occasional touch."

UPDATE Teresa has told Hollywood 411 that she and Zac are "just friends" and that he was just there to support her and see the movie.

Credit: Dahvi Shira for PEOPLE